Tube amp decision?

I bought a Decware Zen Select recently, and the amp is simply amazing!! Although the SL3's are not really efficient enough for it, it provides more volume than expected. Although there is not nearly the bass output of my Odyssey Stratus, the sound is so much more involving. After listening to it for about a month and switching back to the Stratus, the difference is even more noticable. I can no longer listen to the Stratus. It's a great amp, but no comparison to the sound transparancy of the Zen.

So, my next question is, do I get another Zen Select to run mono's or, do I opt for the BAT VK-60? Although, I love the sound, I definately want more bass extension and volume than a single Zen provides. I tried horizontally bridging (or would that be bi-amp?)the Stratus to run the woofers, it did not work well, the gain's were no way near close enough. There was too much bass output. Either a more efficient speaker or more power by bridging the Zen mono's should give me that. With BAT VK-60's selling used for under $2K, that route also seems tempting. It is quite possible that running mono Zen's or VK-60 would have enough gain to use the Stratus to horizontally bi-amp the woofers at the appropriate level.

Associated equipment:

Adcom GCD-750, Melos MA-333.

thanks for the advice,
Paul Woodward