I bought the Belles Aria Signature preamp a little over a year ago, and have been very pleased. Feeding my two older Belles MB200 mono blocks to Vandersteen Treo’s.
Wonderfull combo. The Signature is very transparent and neutral, but with a very full and slightly warm sound David is quite well known for.
If the Signature is also being demoed, I would take a good listen.
I have to imagine your audition is with Johnny Rutan, whom I got my Signature through. Have fun.