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.