you're on the right path. That was me all over, after the Krell experience. the ML sounded like a blanket was on the speakers... Just heard (if you can call it that, it was so brief it was like the dealers electric bill was past due), the 400wpc Ayre monos on Sophias with the Ayre 5 pre, and my previous BAT vk5i pre.... with the BAT pre it got more musical but it had it's stock tubes in it... still it did a better job than the Ayre 5 pre IMO. Sort of dry with either pre.
The McIntosh 402 isn't bad. not at all. Though it didn't really outdistance the vk500 w/BP. They were pretty close actually. the BAT comes off a bit warmer. but system stuff could make either about the same sounding.
The 602 is one I would buy. No question. On the Mac speakers at 86db (LS340, LS360, and then the XR2? THE ONE WITH ALL THE TWEETERS lined up) it was pretty stellar. With the LS 360, having a sub is no longer a thought... maybe not with the 340s. depending on room size. I'd go with a diff pre than a MAC to gain more warmth. Very nice sound however with the top Mac SS pre and Mac CDP, which is how I heard it/them.
For value though, and build, it's mighty hard to beat the VK500 w/BP. Just know this, by itself, the VK500 won't be the end all be all in adding warmth to a system. it'll help, but it's not the complete answer. it's a real chameleon. Mainly IMO the pre, if one is used, has the greatest efffect. The PCs you use with it are vastly going to change it's pallet too.
After a couple years, and several PC combos later, the best I've been able to do for it is listed in my virtual system. the flexibility in driving spkrs by having one is also nice.
Good luck.