Having owned both, I would say the PS Audio M700 monoblock's are a big step up from the S300 and are pretty darn good (esp. for the money). Tube-like is sometimes said about them, but I wouldn't go quite that far. But I would say that they are quite listenable, even for someone (like myself) who is repelled by the thin and edgy sort of sound some folks associate with Class D amplification.
A pair can be had for 2K used plus or minus a couple of hundred. You can also get a pair new with warranty from PS Audio for $2100 if you have something to trade in that originally cost $900 or more. (The key to making maximum use of PS Audio's trade in program is to find something to trade in that isn't worth much on the used market any more but that had an original MSRP near or above their maximum trade in allowance -- $900 for a pair of M700's. It seems unnecessarily complicated --why not just a discount? -- but it's worked well for me several times).
A pair can be had for 2K used plus or minus a couple of hundred. You can also get a pair new with warranty from PS Audio for $2100 if you have something to trade in that originally cost $900 or more. (The key to making maximum use of PS Audio's trade in program is to find something to trade in that isn't worth much on the used market any more but that had an original MSRP near or above their maximum trade in allowance -- $900 for a pair of M700's. It seems unnecessarily complicated --why not just a discount? -- but it's worked well for me several times).
