I've tried three different tube preamps with my W-3 over the last few years. The BAT VK-3i was great, providing lots of tubey goodness, texture, and a huge soundstate. My current Sonic Frontiers SFL-2 is even better detail wise, with a bit less of that 'tubey' sound. My biggest disappointment was an Audible Illusions Modulus 3A; my unit was a nearly new example, but the gain was so high it sounded bright and grainy with the W-3, and had virtually no usuable volume adjustment range. The M3A also burned through pretty much every tube I fed it in short order.