Actually, I got the Syn Res Refs back in Sept 2006. It took me nearly five months to go through ten sets or more of ICs prior to making the choice. I could well have lived with a few of them too... Shunyata's Altairs, the SX's, or VooDoo's Ultralinear. The Res Refs x2's were frankly, a good fit and came in quite affordable to boot... as well as given their retail prices.
I'm of the opinion if it ain't broke, don't fix it. The BAT stuff is here to stay for a time... only the pre is something I seek to upgrade/change and then simply for grater flexibility in selecting sources. the sound quality of it is simply remarkable, after some isoing, and tube rolling, pcs... etc.
It'll be pricey to add the flexibility I seek and retain the sonics it has for sure. Likely, I'll have to move closer to the "dreaded neutrality" monster by so doing.
The amp is a keeper as it was made at the very end of the run of vk500's prior to the release of the 600... so in amp terms, it's still young... and is a real dream by solid state accounts. IMO Though I do wish it would do RCA as well as it does XLR... Oil well.