mono versus stereo ampflication

If the particular stereo amp sounds like crap........it is not likely that his mono clone will sound any better.

Maybe
Better channel seperation (cross-talk)
Better (lower) total harmonic distortion
Seperate power supply for each channel (not always the case tho.)
Mono-block designs are usually reserved for top shelf models or
statement designs.

If in fact , both amps (mono blocks and stereo) are using exactly the same parts and circuitry the differences will be not worth going nuts about.

In short
base your decision on quality of the component, setup requirements and most of all, your personal preferences.

As to recommending a particular amplifier..........
well , there is no easy answer to your question.

Forgot to finish off by saying one builder's stereo amp can cetainly sound better then another's monobloc amps. Impossible to answer that part of your question without knowing the specific amps in question.

Thank you for all your responses. To clarify further my speakers are rated 20 watts to 500 watts. I am considering the Pass Labs INT 150 versus their XA 60.5 monoblocks, which I know complicates things because it is an integrated amp. It is appealing to me becuase it has the new XA.5 technologies in it as best I understand. But the downside is that I really like my current AH preamp. I am not yet aware of a high quality stereo amp in the price range mentioned new or used that I should be considering.
I am further uncertain about wattage - as best I understand if the 60 class A will drive the speakers loudly enough, then is it necessarily true that other things being equal that 200 watts class A would be better sounding?

My feeling is that neither the 60W amp nor the 150W integrated are powerful enough, considering the 500W capability of your speakers, your very large room dimensions, and your interest in music that has wide dynamic range.

If I were you I would try to audition one of the higher powered X.5 (class A/B) amps, as your target selection, and compare its sound with the XA200.5 (pure class A), which I suspect is well out of your price range. Assess how much difference, if any, you can perceive between the sliding class A/B design and the pure class A. I suspect it may be small enough that you will feel comfortable choosing one of the X.5 amps, which provide more watts/dollar, as well as functioning less like space heaters.

To answer your specific question, no I don't think that a 200W pure class A amp is necessarily better sounding than a similarly designed 60W pure class A amp, other than, of course, on high volume peaks that approach or exceed the power rating of the smaller amp.

Regards,
-- Al

What speakers and pre amp do you have in mind???
I would select monoblocks from the choices given so far;keep speaker cables shorter;maybe even use balanced cables if the option exists as longer runs from the pre amp would now be possible if you can not locate the pre amp close to the amps.