Don't bother. I had a pair back in the early 1990s. If you want 1950s sound, buy them. Poor bass performance. Mid range is nice and highs are a bit rolled off. The stock Chinese KT88 back in the day were junk. I pitched them and replaced them with US made 6550. The GE version was robust, the smaller Sylvania sounded like the original US Tung-Sol, but the Tung-Sol was the best sonically and would last forever in the amps. The amps are not hard on good tubes, and a well made 6550 will work great in them. I had the model that used two 5AR4 on each amp. That is the model you want - if you must get them. While I am not a big fan of the "audio experts" for the "big mags", I will admit that Dick Osler's review in Stereophile (back in the day) was spot-on the mark. Read it before you buy a pair. Just remember this, you are basically buying an amp design from the 1950's. Nothing that special, but they are musical and with good tubes, are very reliable.
