CAL Alpha DAC: Stock vs. 24/96 upgrade

The following webpage contains a chart that will tell you what to expect from some popular 12AX7 varients (https://www.tubeworld.com/12ax7.htm). I don't like the Btitish coloration of the Mullard CV4004 personally. My favorite was the Telefunken ribbed plate(NOS) in the Alpha and Sigma. I owned both for a number of years to go with my Delta. I'd also suggest tube rolling and trying a cable like the the Kimber Orchid before the upgrade. If you do get an Orchid: be certain to get one of at least 1m. For some reason the shorter lengths don't get it(personal experience). (http://www.kimber.com/Products/DigitalCables/Orchid/Orchid.aspx)

Hello Kevin, Goto The Tube Store, The heading "Tube Type" on the main page, click "12AX7". Scroll down in alphabetical order till you get to
"M" There you will see this Tube under "Mullard 12AX7", it of course is not a "real" vintage Mullard, but the New Sensor Clone made in Russia.

Great Tube, I really like them in my Alpha, and as I said previously, won't break the bank, and will hopefully stop your search, and desire for futher money being spent on your Alpha. Mark

Approved Audio Service may be the only act left in town, as far as acquiring specific CAL Audio Parts, but may not be the last act for doing Mods-Upgrades.

Great Nothern Sound was one who regularly did substantial upgrades on Cal stuff. I've got a CAL Delta Transport fully modded by them, Blackgate Caps throughout, high speed Rectifiers, and Bybee Filtration.

I did business once with Approved Audio, for a pair of Drawer Belts for one of my Delta's, thinking it was bad, and needed replacing (It wasn't) $5 ea, and $10 to ship them in a little brown envelope. Postage was actually like .72 cents. God forbid what they'd charge to ship back an Alpha to sombody? I got an excuse from them, that it cost thier guy a lot of time to ship that envelope out to me. Mark

Mark, Thanks for getting back. Also, thanks for directing me to the right tube at The Tube Store. I will order a pair of the Mullards. The price is right for me. The cost for a pair is $41.85 incl. shipping. A lot of tubes suggested in the previous posts (Specifically Sylvania 5751 black plates) sound like the real deal but not the price. WHEW!! I found a couple pair of the Sylvania 5751's on ebay & elsewhere. They are hard to find in pairs.

As an aside, I'm curious about how current or previous owners of the CAL Alpha DAC feel about CAL solid state CD players, specifically the Icon II Powerboss. I own one. I've owned SS players pretty much exclusively since I've been buying digital. I'm fairly new to the tube DAC thing. Have you ever owned or currently own a CAL SS player, comparisons to the Delta/Alpha combo, etc. Tube & solid state lovers please weigh in.

I don't know what you're using for an interconnect. If it's not something outstanding- this will vastly improve your combo's musicality (http://cls.audiogon.com/cgi-bin/cls.pl?cabldgtl&1206926128) I owned an Icon II, and when I went to the Delta/Sigma- my son inherited the Icon. When I got the Alpha(and installed the Telefunkens), it was another audible magnitude of improvement(toward the sound of live).