Considering Stellar m700's over AHB2

My core system currently has a Rogue RP-5 tube pre amp, Nuforce class a/b STA200, ZU Omen Def speakers (101 db efficiency).

I love the sound, however, the amp has higher gain than normal and my speakers are really efficient. So tube hiss from the Rogue is significant. I installed a Schiit passive pre to adjust the gain going into the amp and it works great.

I am considering a Benchmark AHB2 (or pair) since they are super quiet and has gain settings. Great reviews everywhere on this amp.

A BHK 250 is something I would love to try, however a bit more pricey. I guess I could find a used one.

My questions:

  1. How does the Stellar series stack up to the Benchmark?

  2. How big of difference between the Stellar series from the BHK series amps.

I love my Rogue RP-5, so I’m not interested in changing. Same with speakers

Any honest thoughts would be appreciated

Switching amplifiers is not going to solve the hiss problem from your preamp. I would suggest finding a preamp with a lower noise floor (signal to noise ratio) as a better solution to your stated problem.

Unfortunately, your hiss problem is all to common when combining tube electronics with super efficient speakers ( 100 dB or greater.)

Your statement that you are not willing to change your preamp pretty much paints you into a corner. Your passive preamp is simply removing signal from your signal path, hopefully affecting the noisy portions more than the musical ones.

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Yes. I expect a little bit of hiss. Anything tube will have some. Especially with super efficient speakers. However, when I place my old BK amp back in…the hiss is barely noticeable. So I am thinking the gain of the NuForce is the real culprit (almost 35 db of gain). I believe the Stellar/BHK are around around 30. I’m only lowering the gain (thru passive preamp between my pre and amp) only 2 db or so. Nothing major. I do not expect zero hiss since tubes are in play.

The short answer is yes, I believe your assumptions to be correct. When you turn down the volume on a preamp you are lowering the signal to noise ratio.

If you live in the USA you can take advantage of PS Audio’s trial/ return policy and try the M700s in your system. That would be to only way to tell for sure, no amount of opinion from this forum will help. Every system is different with too many variables to get a definitive answer.

I used to recommend amplifiers with a gain adjustment on the inputs to solve problems like yours. This was, like you passive preamp, a bandaid solution, not a cure for the whole problem. I have not noticed any modern audiophile amps with gain controls.

A comment on your lowering the gain only 2 dB or so; 2 dB is a lot of signal at preamp signal levels. You also have to consider each connection point, which you have added at least 2, causes approximately 1/2dB of loss, plus the extra cable lengths. I bet you are causing more than 3dB of reduction just by placing the the passive preamp in the signal path. Add any volume adjustment on top of that.

Don’t understand why you want so much power with such sensitive speakers. The manufacturer actually specifies they can be used with a 2w amplifier!

If you want valves in the pre-amp, you could save yourself a lot of time, money and hiss and try a Croft integrated like this:

Holy cow that NuForce has a boat load of gain. I would agree with you that the excessively high gain of your NuForce is the real culprit here.

So, let’s break this down. 4-5 dB less gain out of the Stellar amps and BHK gear should put you in the realm of reason. As you mentioned there might still be a bit of tube noise, though it’s almost certianly going to be negligible.

The AHB2 gives you greater flexibility on gain settings, so it’s likely that it will be able to put the tube noise even lower. Whether or not that matters depends on a lot of factors.

I don’t have a whole lot of hands on experience with Benchmark so I can’t speak to their sound quality.

When it comes to the M700s vs the BHK 250, I find the 250 to be more musical, with fuller sound. Both soundstage wonderfully.

Whether you go with us or Benchmark, it looks like you’ll have a 30 day in home trial, so that helps with the decision making process some.

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I had a Benchmark AHB2 a couple years ago paired with a Benchmark DAC2 HGC. My speakers at the time were Graham LS 5/9’s. I found the amp to be dead quiet. The amp does have a selectable gain switch on the back if you need it. I’m in the same boat now as you regarding amps. I’m thinking about the AHB2 again and also looking at the M700’s. I’ve got a Stellar Gain Cell Dac presently but just got a Benchmark DAC 3 L to audition, which is, to my ears, a jump above the SGCD. I don’t think you’ll go wrong either way. With your speakers the Stellar 300 would be more than enough.

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Thanks for insight. Yes…the BHK would be ideal.

I have borrowed/auditioned small watt tube amps (Decware, etc) with my ZU Speakers. The rooms fills up, however, the amp starts to peter out with loud rock music. I’m sure 45 watts or higher (tube amp) would bring what I want. However, SS can provide that deep growl in bass-low notes. Thats what I like about my current amp which is 80 wpc. I just wish it were a little bit more refined when I listen to jazz and classical. I’m sure the BHK 250 would be the perfect solution. I may have to seek a demo unit and see what kind of price I would be looking at.

Used and demo BHK 250s are out there, just takes a bit of searching. Based on what you’re looking for in an amp, it sounds like it would be the perfect fit.

Keep us posted on what you decide to go for!

I will keep a lookout. Again thanks

MSB S500 and M500 both have a gain switch with three fixed gain levels.

Hardly takes much effort searching. Audiogon is full of used BHK amps for sale.

Actually some good deal on BHK monos.

If you look at the Audiogon listings these are for the most part dealers and dealer offshoots selling under the guise of customers.

Audiogon is an odd assortment to say the least. I did see a couple of what look to be used BHK amps.

Paul, you are right. AG is an eclectic bunch to say the least. A pair of BHK monos that are on AG and just popped on here, only 6 months old looks to be a steal. I wish I could swing that right now. High end, top of the line Monoblocks is what I have always dreamed of when assembling my final system (I’m 51 years old). No, I do not need the power, especially with my ZU speakers, however, something I always wanted. I always fancied a pair of McIntosh 275’s. However, the Macs I’ve heard, although sound fantastic, has a “wool like” sound that is a bit much for me. I think a hybrid amp would be ideal.

No. Not most. Slightly less than half.

I count 20 BHK listings of various flavors on Audiogon at this moment of which nine are dealer sales.

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