Upgrade Nakamichi PA 7All power amp with mono blocks

Current System:

Acoustat 1+1 speakers

Rythmik pair F12SE subwoofers

SPL Crossover (German Brand.  This separates the signal and reduces the demand on the Acoustats.  It helps bring out the mids and highs on the 1+1's

NAD C165BEE pre amplifier (plan to upgrade long term)

Technics SL-1500 C with AT 540ML cartridge in a RigB housing (think AT740ML+)

Marantz 8003 SACD (essentially retired with all CD's on digital card)

Eversolo DMP A6 streamer (occasionally use the DAC, but find it is too bright for extended listening

Schitt Bifrost 2/64 R2R DAC

Nakamichi PA 7All Power Amp (Nelson Pass Stasis design)

I am currently considering replacing the PA 7All with mono blocks, but am also willing to consider a  higher end stereo power amp.  I am looking for improved stage and instrument separation (already very good.  just want more).  I stream Amazon HD (60%), use the digital card for CD material (20%), and vinyl (20%).

These are the power amps I am currently considering:

PS Audio M 700 Mono Blocks ($3498 for pair)

Schitt Audio Tyr ($3198 for pair)

Buckeye Amps ($1550 for pair).  Worried about missing the low level Class A sound (70% of listening is done at low to mid level with 80% primarily background sound).

I would love to test these at home, but with a bad back and restocking fees I am inclined not too.  Once I get a new unit I will A/B it with the PA 7All to confirm it is an improvement.  Trying to minimize bringing too many units into the home.

I would love to hear the community's thoughts on these and potential other units to consider.  I am willing to try used, but it needs to be essentially a lock.  (I purchased the Acoustats and Nakamichi used.  Everything else was purchased new).


Thanks, Ralph


Between the options you listed, PS Audio M 700 Mono Blocks without a second thought. They are a huge leap! You won’t miss absolutely anything from any amp class and wonder why you never heard such sound before. The improved stage, separation, dynamic range and voicing will amaze you. I have a pair, as well as many others from PS Audio.

As far as Schitt is concerned, stay far away.  They are in a much lower league and full of issues!  That's like comparing apples and oranges.  I'll save you the details but will say that I have been there done that.  By the way, you can get the PS Audio for much less $ than what you said brand new. Send me a PM for info on how, if you want.

I can't comment on the Buckeye amps because I never had them but doubt that they will be anything even close to the M700s. 

@thriftyaudio here is a 180 for ya, if you are open to other ideas.  Since you have the SPL crossover now, have you considered trying the matching SPL Elector analog preamplifier instead of your NAD preamplifier?

My thinking is there is more to be heard from your PA7 and Acoustat 1+1s. Having owned Nak amps before, also noting a local colleague had a PA7 at his shop last month for refresh and a few upgrades. Still a relevant amp, imo. btw, I've had RA subs and the exact same DAC you have now, along with a cousin PASS / Stasis amp to yours, in my secondary system setup. Fwiw, I recently tested different tube and matching solid state preamps with mine. You might be surprised trying other preamps with yours.  

@ellajeanelle thank you for your thoughts.  PS Audio sounds like a  decent upgrade for me.  I am also interested in their Stellar Gold pre-amp.  Have you used the Tyr mono blocks, or is your concern with other items in their portfolio.  I found the Bifrost 2/64 compared favorably with more expensive DACs.  That is my only experience with their equipment though.  I was not impressed with the Schitt pre-amp reviews.

@decooney funny you should mention the Elector.  It is on my short list for pre-amps along with the PS Audio Stellar Gold.  I will think about it.  My Crossover came from London (a real hassle, but worth it in the end).  I believe HiFi Heaven stocks the Elector here in the states.  I purchased my turntable and cartridge from them.  They are great.

@thriftyaudio if interested, I can ask my local contact who worked at Threshold for Pass what his charge is to update your PA-7, or what he did on the last one I saw there recently.  Im really enjoying the upgrades on my other Pass Forte amp fwiw.  

Last two times I was there he had 3-4 Stasis amps there as I recall, plus a PA-7. Gotta ship to NorCal though. Super packing and double box and not cheap to ship but he gets amps from all over b/c people want to keep them in play.   



thriftyaudio OP

In response to your question and If I may give you my advice, don’t fall into the trap of taking reviews, comparisons and hype as fact.  Specs can give you a reference but definitely don’t rely on them to tell you how musical any component is going to sound.  I think you’ve already answered your own question regarding Shiit.  I will say that the 3 components that I did try from them were their so-called top of their line and all 3 had issues and got sent back, after I had to deal with what seemed like endless back and forth arguments spanning several days with one of the worst customer services that I have ever experienced.  You are comparing apples to oranges.  My analogy between Schiit and Ps Audio is like comparing Ford to Mercedes.

I haven’t listened to the Stellar Gold yet, but do have the Stellar Gain Cell DAC/ preamp combo connected to the M700s and that sound is what I briefly described to you. I am sure that the Gold preamp won't disappoint you, but you aren’t going to get the full performance of it with your current Schiit DAC.

I jumped from the Stellar to their BHK series.  I bought the BHK components before the Stellar gold came out.  The Gold was released recently. If you are leaning toward the M700’s with the Stellar Gold preamp I’d plan on a new DAC also, but if I was in your shoes with your current assumed budget, I would get the M700s new and a used Stellar gain cell DAC/ preamp.  Unfortunately, the Gain Cell DACs are sold out new.   They will not disappoint, and you have 30 days no questions asked refunds.  You do pay the return shipping though.

@decooney thanks for the offer. My unit was refurbished two years ago.

Well that’s great, and hopefully you can find a good path for next steps. Admittedly,  I was a little hyper-focused on trying different preamps having heard your model amp and speakers (both) at different times, and some understanding of how can they can sound given a great source, DAC, preamp, cables, room etc. Best of Luck on whatever you decide.


Get the M700s.

I've got the M1200s. Best sounding amps I've owned.

Clarity, soundstage, imaging, timbres, top-to-bottom cohesiveness.

Effortless power. 

Check out Van Alstine mono or stereo amps. My friend uses the 2 channel SET 500 with his Harbeth speakers and it sounds real nice!

@ellajeanelle ​​@decooney I have decided to explore upgrading the pre-amp first.  Too many people have said the PA-7AII may be the strong point in the system and that the NAD may be the weak link.  I am focusing on the SPL Elector and the PS Audio Stellar Gold.  Others may get in the mix, but for now these are my focus.  Thank to both of you for your suggestions.

@thriftyaudio given your existing investments so far, I like your plan for yourself on next steps. Since you indicated having just refreshed your PA-7 amp, go for it. Can’t think of a good reason not to try it with either unit you’ve narrowed it down to so far.

Fwiw, I normally run tube pre & mono amps on my main system. Late last year I picked up an older Pass/Forte amp, had it refreshed and upgraded. I’ve been listening to it swapping back and forth since. Channeling your own PA7 lineage that is. I like it well enough to keep it in play, and the tube gear has been sitting idle on the side. And as you know, some of this decision making also has to do with your speakers, but I can share without a doubt, a good preamplifier can really help the amplifier and your speakers to perform differently, hopefully better when you find a nice match and synergy.

As you may be aware, Darren Myers designed that Stellar Gold preamp before he left PS Audio to go join in at Parasound. I was eyeballing the internals and design on that unit, seems kind of like a unique and different design for PSA, lots of "other stuff", regulators, and discrete amplification stages fed by a big transformer in that unit. It might be worth a call over there to PSA to ask them what kind of serious demo they’d let you do, for 30-45 days, ensuring its a "good match" for you and your PA7 before committing to follow through on keeping it. Demo required imo!

Interested in hearing what they do for you. Would be nice to see PSA put their money where their mouth is on this one for you, if you decide to demo it. Best of Luck on whatever you decide.



decooney thriftyaudio OP PSA gives you 30 days in home trials- no questions asked. Even longer if you request. I’ve bought many products from them...

thriftaudio: They also take trade ins. They will discount up to ??% of the price of your purchase if you trade in that NAD! Sometimes more if you have a history with them or under certain circumstances.  For best results, don't buy online.  Call and speak to one of their sales reps.

I have the NAK PA-7A MKII with the CA-7A pre.  Both fully refurbished 2 years ago also.  

Fact is it's a tough combination to beat no matter what your budget is.

"Fact is it's a tough combination to beat no matter what your budget is."



Reading back over this. Another thought along the same lines of thinking...

Yep, levarage the existing amp as-is, keep it for a few more years, at least.   Having owned the BF 2/64 myself, its an ok DAC for the money - yet more to be gained with a 1 or 2 level up dac for sure if you are looking for more lush velvet and musical sound.  Some dacs are "overly precise", too analytical for me, or imo.  

A really good DAC, nice Digi Coax cable, nice output interconnects to the PA-7 II, and you'll hear the existing amp and Acoustats in a new way.  Demo 3-4 more dacs first.  Try this for a while, might be pleasantly surprised.  

Then, after this is set up well, IF the new-amp-itch is still there for a set of "monos", start demoing (buy/return/keep) and comparing decent monos to see who can dethrone the recently refreshed PA-7 II.  Would not be suprised if it holds its own.  



We seem to have similar taste.

I am picking up a used Benchmark LA4 preamp this weekend.  I leveraged the purchase to also pick up a pair of PS Audio M700 power amps used.  I suspect the LA4 will be my long-term preamp, but I will do some a/b testing with the NAD just to comfirm.  I have some interested parties in the NAD so it will be easy to sell.

I will also do some a/b testing with the M700s with both preamps just because the equipment will be here.  I expect I will leverage them into something else, but if I love them then I will leverage the Nak into something else.

My streamer/DAC journey was a mess.  I started out with a Cambridge CXN v2.  The sound was just OK and the app was not user friendly.  Never could get it to work consistently.  I returned it to the dealer and tried the Node N130.  The app was a little better and the sound was about the same.  I upgraded the N130 with a PD Creative SMPSU in a LPSU interface.  The sound improved dramatically.  Really loved it.  While this was happening I ordered an Eversolo DMP A6 based on all the great reviews.  By the time it arrived the upgraded Node was working great.  I was going to return it, but decided to go ahead and do an a/b test.  Turns out the streamer portion of the Eversolo worked better than than the Node.  Additionally, the app was amazing (still is).  The DAC portion was a bit shrilly, but it had very good stage and instrument separation relative to the Node.  I kept the DMP A6 and moved the Node to a secondary system.  The Node is still very good.

I listened to a friends Lumin D2 and liked it, but didn't love it.  The sound was great but the app was not as user friendly as the Eversolo.  It was also too expensive for me at the time.  My friend suggested the Bifrost 2/64.  He had one on his 2nd system and said the DAC was the equivalent of the D2.  I listened in his system and liked it so I ordered one.  I was prepared to return it if I was not blown away in my system.  I was.  It was a huge improvement over the DMP A6.  

So, what did you try in terms of DACs and where did you end up?  Did you try the Schiit Yggdrasil LIM or MIL?  Any suggestions for the future?  Did your try different streamers too?



@thriftyaudio I see so you’ve partly been down the dac merry-go-round. I ended up leveraging a bunch of friends and colleagues to narrow down my lists a bit more. You or others might prefer something different in terms of DACs, I was following along with folks at Schiit for while, and almost went down the Yggy path, yet had some insight to go a different way, and was trying to stay a way from a huge dac footprint, and a few I compared with that owned Yggy had downsized to BF 2/64. Dont get me wrong that dac has decent deail, separation, just not the velvet and musicality I was looking for. (note: I’ve had modded MHDT Labs tube tube dacs before as well). Note Schiit Yggy, probably a little smoother yes, yet maybe a different sound from BF 2/64. For streamers, nothing special, an older/updated Arcam unit I won’t let go of, and have compared it to a few different Bluesound Node units through friends. I was looking for a particular result, and a certain magic for my modded Pass/Forte SS amp and my upgraded Quicksilver Mono 120 tube amps. This eventually came about through my Border Patrol SE-I dac with the upgraded power supply, specific phillips TDA1543 chip, and Jupiter caps that come with SE-I version. Its the only dac I’ve never modified or needed to. The Tube is not in the signal path, which I like for my needs - its part of the power supply circuit and you can turn the tube on/off for different sounds too. Gary Dews built it for me and super happy pairing it with my particular pre/amp system setup. It responds well to different cables, and now my digital woes are over. Have not looked back since. Some people try it and rotate it too fast without letting it fully settle in. After 45 days of solid play time, it opened up more, and it bested my other dacs in a nice way. Let me say its a "preference" thing, and does what I want and need for my system.

I do believe so much of this is system/speaker dependent and finding a good match for your current and demo amps in the way of the right dac for you can be a game changer. It was for me. 👍