I've never heard the first setup you mentioned, however I have heard what the Musical Fidelity A5 and 805s sounds like together with a Naim Cd player. I have owned and operated the Musical Fidelity A5 Integrated amplifier in my stereo system since April 2006, paired with the Naim Cd5i, and Paradigm Studio 100 v.2's. I became a little curious as to how my MF A5 would sound on a set of B&W's, so I brought my amp into my local dealer to have a test drive. I did my test on a pair of B&W 805s', and 803s'. I played everything from rock to rap, to classical. My first impressions were that the A5 was very capable of driving both the 803s and 805s with ease. The sound was very, I stress very open open and instruments were played somewhere between the speakers and perhaps a little behind the speakers, giving me a good concept of depth. The 803s' had a little deeper bass, however so slight on classical music. The 805s, excelled at keeping rhythm, the sound was lighter and as a result seemed to image better. (I tend to find bookshelf speakers image better than tower speakers) The A5 was able to power the 803s' with ease and could throw at them whatever they could handle. The A5 was able to push the 803s' until the point they sounded like they'd had enough and began sounding muddled. The A5 never broke a sweat, nor sounded strained, I knew the 803s' had their limits on very bass oriented tracks, as my Paradigms never sound muddled no matter the listening levels. The 805s' sounded very open, energetic, lively and willing.
If one were to try the A5 and 805s', they would not be dissapointed. The A5 is one of the best amps you can buy, regardless of price. The 805's are one of the best bookshelf speakers you can buy at any price also. The A3.5 is also another option, if you decide to go with the 805s'. The A3.5 will have ample current and wattage to drive those bookshelves. The A3.5 has the exact same circuitry and design used in the A5, and also lends the dual monoblock design. The A5 was ample to drive the 803s' and the 805s' seemed like a piece of cake for this amp. Dont' get me wrong, there's nothing wrong with going with a more powerful amp, if anything, there won't be too much of an audible "loudness" difference, but there will probably be a more in-you-face, more presence to the music. Just a thought if you want to save a bit of money, but if you've got the A5 in your budget, go for it.