I recently acquired this piece along with several other items of audio gear. It looked brand new except for the missing 5AR4 rectifier & EL34's. I looked it over for any other potential visible problems, including the underside. All looked like new. There's a hand written script on the inside of the bottom panel that states: Steve Hall Svcd 2-2-93. I do not know who Steve Hall is and a quick internet search did not help.

I have replaced the missing tubes, checked the two 7199 tubes. The EL34's are a new, matched quad of Valve Art tubes. I set the bias and hooked the amp up to my system & speakers and it worked & sounded just fine.

I played this for more than 36 hours and re-set the bias. The new tubes are now burned-in and should be stabilized.