BHK preamp vs Sonic Frontiers Line 1 -- Will I be wowed?

I am thinking of buying a BHK PreAmp, but because I do not live in the USA, I cannot take advantage of that wonderful “try it and see if you like it” approach and this for me when done is an 8k+ CDN purchase. (come on Paul, we are on the same darn continent)

Will I be wowed is my question.

  1. This preamp will be replacing a Sonic Frontiers Line 1 Preamp that has been upgraded about every 5 years (Parts ConneXion) to be the best it can be for over 20 years now, so yes, it is old but it is venerable. (Paul always speaks so highly of Sonic Frontiers)
  2. BHK Preamp would be joining my system whose basic configuration contains a pair of Focal Sopra 3’s and a pair of Bryston 7B3 Monoblock amps. This combination of speaker and amplifier (for 2 channel only) in my estimation needs to be “warmed up” a bit but I do like the quickness, clarity and blackness of the speaker/amp combination.
  3. I have tried other ‘solid state’ only preamps as of late but I think I enjoy a tube front end better.

While I have not heard the Sonic Frontiers tube preamp, I have lived with a Conrad Johnson PV10AL tube preamp for 20 years mated to a Conrad Johnson MV55 tube amp. The BHK Pre is cleaner and more neutral sounding, has cleaner and deeper bass and has some of that tube midrange magic. I like the BHK Pre alot but also still like the midrange qualities of the CJ tube preamp too, and will never get rid of either preamp. The BHK pre is mated to PS Audio M700 solid state monoblocks and am very happy with the musicality of this combo, even after living with the CJ tubes for 20 years and really enjoying the musicality of the CJ tubes.

@Mesonto I would ask Chris at Parts Conn if he has any demo BHK Pre’s for in home demo. I know Audio Eden had an option, but you need to basically pay for the unit upfront, just in case you decide never to return. When I was looking to purchase mine, PC did not have an available unit for loan. I eventually found one on the used market which was considerably cheaper than either of the places above, but PC usually has decent deals. Never owned a sonic frontiers, so can only comment on the BHK. It sounded wonderful with my HP Primaluna 8x kt150s, but really shined with the addition of the BHK250 amp. Next move mono 300’s. Best of luck.

check that… It may have been Audio Excellence with at home demo…

I thoroughly enjoyed my Sonic Frontiers Line 1 preamp, a wonderful piece of kit. I miss the neat remote.

I think you will be enjoy the BHK, but they are both excellent. You really need to listen to the BHK before making a decision, as already suggested.

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I own a fully upgraded Line 2 SE+, last at PC for upgrades 7/19, and a BHK preamp. While they are both excellent preamps in their own right the BHK sounds best when paired with one of it’s running mates and the SF is a bit more versatile in terms of what it works with. Neither of them are much on the warmer side of neutral to my ears and I have used both of them with at least a half dozen different amps and almost that many different speakers and the impressions of them remain the same regardless of the pairings. Depending on how much you are to trying “warm things up” you may be best served by a 6SN7 based preamp or at least one that is known to be voiced to the warmer side of neutral. My opinion in my systems and I’m sure you’ll find I’m in the minority here.

I have the same set up as adifferentpaul PS Audio wise. Couldn’t be happier tho I’ve been thinking about the M1200’s. You can’t go wrong with the BHK PRE!

For what it is worth, I own a Sonic Frontiers Line 3 SE+ with Parts Connexion’s Platinum Plus upgrades (which include DUELUND CAST-PIO-Copper inter-stage coupling caps).

About 2 years ago I ordered a BHK Pre. But after several weeks of listening back-and-forth and finding it not to be in the same league as Line 3, I returned the BHK Pre.

The difference wasn’t just subtle, either. (Yes, I was interchanging same tubes at several points of my comparison-listening to help reduce the variables).


Ahh, the second comparison. This is what I was really trying to figure out. I still will try and get a sample unit from a local dealer but your experience and one other’s really makes me think. 8-9k taxes in is a significant purchase especially if they are comparable. I would not want to make a sideways move or as you say take a step down. Thank you.

FWIW Changing the caps in a preamp can have a dramatic impact on the sound. It can make your preamp several level higher in sonic performance.
I changed the four cheap Solen caps on my Bruce Moore preamp to Mundorf caps and the transformation was very dramatic!! Sounds like a much more expensive preamp after the change!! The rest of the caps in the Bruce Moore were Rel and Infini Caps, which are already great caps so I didn’t touch them. I were going to use Duelund Cast, but they were too large and expensive.
My brother also had a Aesthetic Rhea phono preamp and he sent it back to the factory for a upgrade to Signature statist. They changed the original RELcaps to DynamiCaps in his unit and a few other things and it was night and day difference in sound!! Now it sounded world class!! It also cost him $3000 for the upgrade!!

You are right; Duelund Cast run quite dear price-wise, and the upgrade involved 4 of them. But – my, oh, my – what a difference!

I know someone who changed his Acoustic Zen speakers with Duelund Cast caps and Duelund Cast Graphite resisters and completely transformed the performance of his speakers!! Imagine if they put these caps and resisters in the BHK preamp!! But some Duelund caps cost thousands each so maybe the BHK might cost a bit more and put it in another price category.

So after talking to a former dealer of Sonic Frontiers equipment (from a long time ago) who presently sells PS Audio equipment and from your experience, I have decided to upgrade my Sonic Frontiers Line 1 to an immaculate SF Line 3 (which amazingly enough just went on sale as of today) and I am going to have it upgraded at Parts ConneXion.

The dealer simply said this: “You can always get the BHK Preamp, but it is rare to be able to buy a used SF Line 3 preamp”. He went on to say that he thinks the BHK Preamp is very good (their BHK 300 monoblocks an even better deal) but that he believes that a properly attended to and upgraded the SF Line 3 is simply a better sounding preamp. He left me with the advice that I can always take home the BHK Pre to compare it with after I have everything settled.

And this is exactly what I am going to do.

So I now own an un-upgraded SF Line 3 and an upgraded (SE+) SF Line 1. I am going to compare these 2 preamps first, then I am going to upgrade to the SF Line 3 to the “SE+” version. At which point I am going to ask my dealer to let me borrow a PS Audio BHK preamp to do an A/B comparison of both…

Either way, if I have to sell my SF Line 3 SE+, I won’t lose much and I will have had the opportunity to try both.

This hobby is expensive and time consuming!


You will love the Line 3 once you put good tubes in it. The original Sovtek were horrible shrill thin. I have had a Line 1, Line 3 and now a SE+ Line 2 that Chris worked for me last year. My first SF Line pre was in 1997.

In my personal opinion, the 2 is a big step up from the 1. And the 3 is a much much smaller step up from a 2. Many of us SF aficionados feel the 2SE+ sounds better then an old original 3. Regardless, get Chris to upgrade your 3. Not just for sound, but to insure trouble free use.

Tubes are critical. On the line 1 and 2, the middle two 6922/6dj8/7308 are the sound critical ones according to Chris. He can tell you about a L3.

Years ago, while at Genesis, I stumbled across Amperex 7308s JAN, in my research, USA made late 60s. I have had them in every SF Preamp since.

Recently, during my Covid clean out, I sold a “spare” long boxed up Line 1. It had no tubes. Looking in my tube stash, I found 6 NOS RCA 6dj8 from 71. They were rebranded Amperex Dutch 6dj8. I picked the best two, both internally and matching, for the middle two, cleaned the 50 year old pins and hoped for the best. Maybe I was not expecting much, but I was blown away. No, not the same as a 2SE+ with 7308s, but all the attributes of SF Line preamps. When the buyer can over to listen, it sounded so good, I think he was afraid I would change my mind on selling.

The point of the long winded diatribe: SF Line preamps greatly benefit from both tube rolling and careful matching.

By the way, my Line 2se pairs wonderfully with my m1200s and my new Stellar Phono. Great synergy.

Have fun!

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You are going to have fun!

Please keep us filled in.

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Yes, quite an odyssey you are about to embark upon!

And worldwidebeagle is right about the two of the 6922/6dj8/7308 tubes that are so critical for the best sound. These are the ones in the LV1 and V2 sockets and the ones to play around with, if you care. I am presently using a pair of Siemens there from the 60’s with gold-plated pins that I serendipitously lucked into. (I say “serendipitous” not only because of a real and quite special kismet I found these have with this particular preamp, but also because – as I found out years later – Parts Connexion had misidentified them when they sold them to me; these are supposedly even rarer and more desirable!)

The other 8 specimens of this particular tube family that the Line 3 uses apparently matter far, far less to the way it will sound. Am still using the steel-pinned Tesla ECC88/6DJ8’s that came with the unit when I acquired it used 6+ years ago. Here was Chris Johnson’s advice to me then for replacing those tubes down-the-road: “The last 4 pairs are all cathode followers (no gain - just reduce output impedance)….our Russian mil-spec 6922’s (6H23p-eb’s) are perfect in this application. Should all be the same.” In particular he liked their “VERY low noise”.

So I just got back my updated SF Line 3 from Chris at Parts Connexion. I ended up replacing the main capacitors, doing the volume mod, replacing 4 RCA jacks, a few diodes, the phono jack, etc. All for a measly $1.4k CDN. (no tubes though because the main ones were freshly replaced before I bought it) I brought it home reinserted it into my system…

— I was completely blown away!!! —

It was just as big of a difference going from my SF Line 1 to the Line 3 without the mods as going from the original SF Line 3 to the one modified one. This preamp is truly well beyond my expectations. The internal upgrades have made every source sound immeasurably better. The bass, the openness, the transparency, the soundstage, and the quietness of it are well beyond what I have ever been able to get previously. (the soundstage has really been perfected) I am simply blown away and I am going to spend my whole freaking weekend relistening to my music.

Come next week I have an appointment with an audio store in Toronto to “borrow” a BHK preamp for comparison. This should be interesting. I cannot wait to see if I have done the correct thing. So far the SF Line 3 has set me back about $5K CDN.



I had a Line 1 and loved it. I should have kept it.

I wound up buying a used Balanced Audio Technology VK-50SE instead of the BHK Preamp (which was ny original “go to”). Looked at some used SF gear but since all my gear is fully balanced, BAT was my choice. So happy. Loved Sonic Frontiers stuff since I was a kid. Even had Chris give me a tour back in '95 (I was looking for work fresh out of Mohawk College) while ordering Caps/Coils for my homebrew Speakers.


I’m looking at both BAT, SF, McIntosh, and PSA for my tube pre needs at the moment. Eager to see how this plays out.