I have been a tube enthusiast for many years.I started out with solid state but once I heard tubes in my system;I was hooked. That midrange warmth is hard to beat .
Prior to auditioning the M400’s I had added the PMG Pre & DAC to my system. Lucky me! The PMG Preamp was a game changer & as I expected, the critics have universally agreed.
Since the DAC & Preamp made such an improvement to my system, I put my name on the waitlist for the M400’s. When they arrived I hooked them up & listened to them briefly. I wasn’t impressed. I was going away for several days so I kept them running at a low volume for 6 days. Upon return, I listened to them again; they had noticeably improved but not to the point that I was convinced to keep them . Yes, they sounded better than my other amps but factoring the cost not enough to convince me to purchase. I decided to shut them down for a couple of days. When I restarted them there was a nice gain in sound quality but again not enough to convince me to open up my wallet. I ran them continuously for a couple of more days before sitting down for an extended listening session. By this time I had about 180 hours on them. About half way through this session there appeared to be a very noticeable jump in volume so much so that I literally jumped . My sound level meter reading disputed this but there was definitely more information. Things were starting to get interesting.
A few days after this a very experienced audiophile friend visited for a couple of days. He arrived in time for lunch. After lunch we listened to the system from 1pm until dinner at 6.My friend liked the amps but he also liked my other amps. I kept the amps running during dinner. After dinner we spent another 4 hours listening and the amps were really starting to cook. My friend was really starting to enjoy what he was hearing. He said it was like he was in the mixing room when the recording was done or you were at a live event.He had never heard a system sound as good. After we shut it down for the evening he said what he had heard during the evening session was magical and I had to agree.
The next morning for comparison purposes I connected my tube amps. To warm them up we watched a concert video. After the concert, I played 3 songs we both know well. He stated that after what he heard the evening before , the tube amps and sounded flat and again I had to agree. I then connected my class D amps which require very little warm up time. We played the same 3 songs and he liked what he was hearing compared to the tube amps. I then connected the M400’s & played the same 3 songs. At the end he said “I know these aren’t inexpensive but after what I heard I would buy them. After what I heard the previous evening I was already convinced. Magical is the perfect description for what these amps brought to my system.
If you are still reading this I will get a little more into the sound quality. Compared to my tube amps the bass is deeper more solid & accurate as were the highs which I expected but it is the midrange that closed the deal. It doesn’t have that golden honeyed tube sound but it sounds much more like you are there. One recording I use for evaluation is Emmylou Harris’s Spyboy album. Her band included one of my favorite guitarists,Buddy Miller. It is an excellent live recording.On the song Deeper Well which his wife Julie wrote his guitar playing is astonishing. My other amps did not do this song justice as they tend to gloss over his playing but the M400’s more than did Buddy justice.
In summation these amps took a long time to break in to the point that I was unwilling to part with them . I continue to hear things in songs I have played for years I never heard before. They are very detailed amps. The soundstage is wider ,higher & deeper than I have ever experienced in my system.
My speakers have a sensitivity of 97 db & I listen at 85 to 90 dba so there is a good chance that what I was listening to was mostly if not entirely in class A . They do generate some heat but not anything close to the class A amps from Krell I have had & I do appreciate the lighter weight as I get older.
Initially, I planned on giving these amps 100 hours of run time before making a decision. Thank goodness I gave them more than double that.
Thanks for this detailed comment on the amps. Love it! Of course, I go straight to the punch line:
"In summation these amps took a long time to break in to the point that I was unwilling to part with them . I continue to hear things in songs I have played for years I never heard before. They are very detailed amps. The soundstage is wider ,higher & deeper than I have ever experienced in my system.”
I will note also that another paragraph down you speak of the burn in process at 100 plus hours. We are currently building a burn in system that will put every PMG product we make through about 120 hour burn in process before ever leaving the facility. Certainly a good head start and one we’re increasingly believing is the way to go.
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Paul McGowan
CEO PS Audio
www.psaudio.com
The new Audiophiles Guide
Thanks for the kind words & excellent products. I have to stop drooling over the FR 30’s or I will be in real trouble ! The extended burn time on the part of PS Audio is very generous on your part . I am glad that I don’t have to pay your electric bill!
Or exhaust the heat! Our engineering team is working on how to vent the space in production where everything will live for essentially a week. And then, yes, the electric bill! Fortunately, the entire roof is filled with solar panels so that helps, but not so much at night…
Thing is, we can catch any problems but, more important, we can deliver products that are already burned in and that’ll be huge for folks. And us.
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Paul McGowan
CEO PS Audio
www.psaudio.com
The new Audiophiles Guide
When I helped clients with the layout of a new production facility I suggested that they install their heat producing equipment usually air compressors next to their shipping & receiving docks. They had an outside wall that they could easily exhaust the heat out in the summer & then another fan could blow the heat into the dock area in the winter.
Iwin1949, which speakers do you have?
I have a pair of modified Tekton Design Ulfberht’s.
Awesome!! I hadn’t heard of these speakers before, so I had to look them up on the Tekton Design website. An unusual design and the posted reviews are very positive. Paired with PMG m400s they must sound really good! 
Thanks they do sound great. I have them paired with a couple of Martin Logan 212 subs. They have a great performance to cost ratio.
Some final thoughts as I now have well over 300 hours on these amps. The online photos don’t do them justice. Compared to the M 800’s they do look small but they are anything but as the attached photo demonstrates. They not only sound great, they look great.
The you are there sound is addictive & why I eventually decided to purchase them. They are just so natural and realistic sounding they just draw you into the music.I have and have had many amplifiers but these are the best by a good margin. Unless, I purchase some inefficient speakers the M400’s are probably my end game amps, they are that good.
Wow, thanks. There’s no better recommendation than "Unless, I purchase some inefficient speakers the M400’s are probably my end game amps, they are that good”**.
Of all the platitudes and compliments these amazing amplifiers have garnered for themselves, this one really rings the bell. And I find that particularly amazing because power amplifiers, as a category are one of the last upgrade paths people make.
I think I’ve waxed on about this before. Back in the day when everyone had a tube amp because there was nothing solid state that mattered, this wasn’t true. Amps were exchanged as often as preamps and the sonic differences were enormous.
Really interesting to have witnessed this over all these years. Anyway, I ramble. Thanks for chiming in and congratulations on your new amps!
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Paul McGowan
CEO PS Audio
www.psaudio.com
The new Audiophiles Guide
It’s interesting that some still think 100 hrs of burn-in is enough to break-in a piece of audio gear. In my experience the minimum is 500 before critical listening, and another 500 before everything is completely flushed out and sounding its best.
Glad to hear PSA will be putting at least a 100 hrs on each piece of gear before shipping out.
I would think that’s the minimum for making sure there are no issues with the unit.
The burn in racks for amps are almost ready and I believe current production is using them. I’ll give you final results after everything is implemented and the production engineers put their stamp on it, but currently the plan is a full week of burn in under load which is, what, 160 something hours?
Be interesting to see but, as you point out, it sure ain’t gonna hurt!
Hello Paul,
I have about 100 hours on my M400s and they are sounding quite nice. I need to reserve final judgment because I got so unlucky as to have my ARC Ref6 SE experience a failure, maybe with that 6550WE power tube. It happened only after a few hours of playing the new amps. So I’ve been using my PMG 512 DAC it’s place, using the variable volume. One thing that really stands out is that piano classical pieces have suddenly become much more interesting to listen to. Naturalness, transient attack and especially lower register weight is much more realistic now, as compared to my BHK 600s. Steve Guttenberg touched on this in his review as well. Barbra Streisand’s voice has a very powerful upper midrange presence and for once it does not sound harsh. I’ll have more to say once I get my preamp back and dare I say, the PMG preamp might be in place for a comparison.
Peter
Thanks, Peter! Sorry to hear about the Audio Research problems. You’re hearing exactly what I am hearing too. Darren’s designs just keep blowing me away and, for those of you that don’t keep up with all this, our chief engineer, Bob Stadtherr, put so many months of time and effort into the amp’s development that I am gobsmacked.
I know most people don’t really care a whole bunch about how the sausages are made
But being right in the middle of it it’s always a fascinating bird’s eye view for me.
When Darren hands over one of his circuits that we’ve all auditioned and approved, it then has to be made into something we can build and can be reliably be put into the field and perform at its best for decades.
To watch what goes into that is always an inspiration: like synchronizing the multiple output PCB modules together so they all contribute evenly as well as thermally track, have the same Class A’ness ( 
), distortion specs, protection, and so on. And each of the subsystems has to report its operating parameters and well being to the “rain” inside so it all keeps smiling.
I could go on but I won’t. Thing is, way back when, in the Phase Linear 400/PS Audio Model One days of the 70s and 80s, there was none of this sophistication. It was the fracking Wild West of circuits and we prayed they’d live through a night of playing.
Fun!
Glad to know I am not the only one who experienced this. Some of these components took forever to reach their peak level.
Even my little jumper for the top box of FR30 seems to improve slowly too. I have it installed five days ago, and yesterday it sounded the same as the day before. But today there is a jump in SQ again!
In hindsight for these amps 100 hours was not nearly enough. I assumed that PS Audio had already done some extensive burn in. If they had done even 120 hours my 100 hours would have been enough. There are also a lot of variables here. What are you playing to break in the gear? Classical music is going to demand a lot more from gear than folk. Volume level also matters.The type of amp also makes a difference. My 14 pound class D amps are a lot different than some back breaking class A amps . Some DAC’s seem to take forever & some don’t. Same goes for cables.
In break-in their are no absolutes unless you don’t believe in such a thing as break-in.
Sent my BHK 300s back today. THe M400s rule! I had several transcendental experiences after 300+ hour burn-ins. Like another poster here, I was initially unimpressed in comparison. Didn’t listen very much in the burn-in period, but now, WOW! The whole front of the room is alive!
BTW, the M400s are a bit longer than my P10s they sit on. Fyi.
Paul, am I correct in thinking that you’ll have a set of racks to take the various International 230v amps? Also, will you find a way to have enough International 230v amps such that delays in shipment to distributors aren’t badly impacted?
I am sure Paul will correct me if I am wrong, but I believe Delia told me that because of the design of the power supplies used in the PMG amps, there are no separate 120v and 230v amps – one amp covers all power sources. The only difference is the power cord they drop in the box when they ship it. (Clarification: And I’m suggesting that it should make no difference what the incoming mains voltage is for the purposes of burn-in.)