I was fortunate to find someone who had several NOS types locally. I tried RCA clear tops, GE clear tops and Sylvanias. the GEs were the best - just a tad stronger and fuller sounding than the others - and I wound up buying a second pair just to have on hand.
AJ, you're right about the volume. I can only take this up to about 1/3. I bought this pre-amp because I needed something decent and reasonably priced in a hurry, although I do like the way it sounds. I may look into those mods in the future. We had it hooked up to a buddy's SS amp last weekend and the sound was very impressive - especially considering the price, which was just a few hundred bucks.
AJ, you're right about the volume. I can only take this up to about 1/3. I bought this pre-amp because I needed something decent and reasonably priced in a hurry, although I do like the way it sounds. I may look into those mods in the future. We had it hooked up to a buddy's SS amp last weekend and the sound was very impressive - especially considering the price, which was just a few hundred bucks.