Tube upgrade for Unison Research unico

The unico will be my first tube amp(coming next week), so I am a tube beginner. Does anyone have experience with a tube upgrade for the unico? What sonic improvements will how much money buy? What tubes should I consider? I listen to everything, but most important is how acoustic instruments sound, high resolution, their smoothness, their attack, their harmonic richness & warmth.
Contact Kevin at Upscale Audio ( ). Kevin carries the Unison line and is an expert on recommending upgrade tubes to fine tune the sound to your taste.
I use mullard cv4003.
Kevin from upscale audio recommended to me.
Very sweet midrange!!
Use Telefunken tubes if you can !!!!
Mullard and Phillips are good too !!!!
And put the HALO dampers which will take your sound in higher level for sure !!!
You will find dampers at :
Here's an alternative view ... avoid the cv4003 tubes, or any advice from kevin at upscale audio. He's earned himself a horrible reputation with a lot of tube-o-files for selling crap and misleading people in order to unload inventory.

Example: the cv4003 tubes, which he heartily recommends (and charges more than his competitors) are 1980s vintage and not even made by mullard. They are made by various companies that bought mullard's tooling and trademarks, and they sound shrill--typically better than contemporary tubes, but nothing like vintage mullards.

If you want excellent advice and better prices, i'd recommend the guy at Vintage Tube Services. He gave me the straight dope, and when I told him I couldn't afford the vintage mullards he recommended some vintage RCA black plate tubes. He sells some that are used (but that still measure as new) for a serious discount.

Anyway, these vintage RCAs sound head and shoulders better than the cv4003s that i used. In general the cv4003s sounded a bit better than the stock tubes .. a little less hard .. but they recessed the midrange and took a lot of meat out of the vocals. The RCAs as smooth and warm, no complaints. If you can afford the vintage mullards, these are supposedly even better by quite a bit.