Bryston 4B3 or Ps Audio M700 monoblock?

About 4 months ago, I replaced my classic Adcom 555-II amp with the PS Audio M700 mono blocks, and I have been very pleased with the upgrade in sound. The M700s are very clear, dynamic, and musical while running cool and not requiring a strong back to move them. Stereophile calls them "an outstanding bargain," and I enthusiastically agree. 

I am sure that the Bryston 4B3 is a strong performer, but it is also significantly more expensive than the M700 pair. I have not heard the Parasound A21+, but it would have been my second choice when I bought the M700s. The issues that drew me toward the M700s (in addition to the great reviews) were the fantastic discount available if you have any gear to trade in and the 30-day in-home trial from PS Audio. If you want to demo the M700s before you confirm your purchase, you can try them in your system and see if they create any magic with your gear. If they don't, just send them back. 

Good luck with your search for a new power amp!

Thank you for your comments.

By concerned I meant that although better than previous 4Bs, it still can be dry (i.e. less warm) compared to other top other class A or AB. In general I have been very happy with the 4B SST except for some dryness in the midrange and some harshness in the top midrange and treble. I mitigated this with a Rogue Magnum 99 tube preamp and the combination was great to my ears.

However, if I am getting a new amp, I'd like to get an amp that does not have those qualities, and although the 4B3 is supposedly better in this regard, I am not sure if it is better enough to my taste. Both PS Audio amplifiers are described as organic sounding and the M700 was even called tube-like. Was hoping someone who heard them and the 4B3 might comment on the differences.

I may very well try the M700 at home. I do not think I can do the same with the Bryston. 

I've had the 4BSST for 15 years.  Most of that time I used it with a Conrad Johnson tube preamp.  Then I bought a BP20 with the MPS1 and finally gave up on that tube noise. 

Recently I bought the 7BSST2 monoblocks with the BP26 and MPS2 for a total price of 6500 bucks to my door which I thought was damn good.  Soundwise, it's a huge improvement but in fairness to the 4BSST the preamp and power supply was a step up so it's a bit hard to know how much the monoblocks helped. 

My advice based on what's available is to negotiate for a pair of 7B3 because there are a lot of them now on Audiogon at pretty decent prices.  The warmth factor or whatever versus the 7BSST2 is hard to define but I trust Bryston and you are getting almost 20 years left on the warranty.
Seriously, PS Audio?  Cmon man.

I tested out a set of 7b3 monoblocks in my system.  I would say that the Cubed B3 series are not dry like the previous versions.  It's definitely a lot better sound, sweeter sound even.  Very high resolution amp.  However, I think it keeps the similar Bryston sonic signature which can be somewhat thin in the midrange and midbass/bass.  I generally recommend matching Bryston amps to a very warm/full preamp and use lots of pure copper gold-plated wiring.  A Marantz preamp would be great.

If you want to move and are looking for a fuller midrange, the Stellar Gain amps are very nice.  I have heard them and they are definitely more conventional sounding than the thin/fast Brystons.  The did not sound bad to me at all.

I suspect that the Bryston 4b3 will be a higher resolution with more "air", but may lack in midrange body and fullness that the PS Audio M700 amps would provide.  So in the end, it really depends what you want.

The Parasound A21 amps are very nice as well (I have owned A21/JC1s one and actually have an A21 for sale).  They are much fuller and natural sounding than the Bryston or PS Audio M700, but they are soft/rolled-off in the high frequencies.  The PS Audio M700 are probably the most neutral sounding of the three.  The Parasound would be just slightly on the warm side of neutral.  So, again, it depends on what type of sonic signature your looking for.

@benjosef1, if you get a chance to hear the 4B3 I will guess you will be very pleased with Bryston’s latest level of refinement.  I own a Pass 250.8 and after changing speakers was tempted to downgrade to a more environmentally friendly amplifier and purchased a used 4B3 to compare with my 250.8.   The Bryston was very smooth with no hints of harshness in my system.   I was very impressed with it and thought it competed well against my Pass amp; I also thought it has slightly more detail along with a tighter faster bass than my amp.   In the end I kept my 250.8 and sold the Bryston because the Pass offered better front to back soundstage and has a fuller more life like sound to my ears.   The 4B3 was very nice though and well worth its price relatively speaking; especially when you throw in the warranty and build quality...