i just outfitted these puppies with brand new 12Au7's. (one for the compressor and one of the preamp) you can have both units for $150. buyer pays shipping...
for two nice pieces of gear - These don't get the credit they deserve as for some reason ART has a "funny" name on this board. Please check out the reviews on Harmony-Central. The Tube PAC is the preamp/compressor circuit of the ART Tube Channel. Pair these with a Tube EQ and you'd get the entire channel.
They are excellent as channels for Bass/Drums/acoustic guitar/overheads/etc. They are amazing D.I. boxes for the money as well as instrument tube preamps. Yes, the stock tubes are a crapshoot - spend an extra 10.00 for a JJ ECC83 for the preamp stage and/or a Philips 5751 for the compressor stage.
In case you've missed it - these are actually increasing in price at the internet vendors - pretty tough to find one new for less than $115 now.