antique sound 1009

There appear to be some uninformed answers above.
I owned the 1009's for a while and they were quite impressive in my system. They are not knockoffs of anything. While the some of the amps listed above may have better fit and finish and a fancier chassis, most of them simply don't perform as well as the 1009. NOS 845's are completely unnecessary with this amp. I found however that substituting the EL34's for the Svetlana winged C offered a more even tonal balance in my system.
I have owned several of the amps listed above and the 1009 was the best of the bunch. (CAT and Lamm would be better choices but at several times the price of the ASL). The review of these amps on Salvatore's High-End Audio website is mostly accurate in my opinion.

Tab, the later version of these amps have the caps that are recommended. One could install expensive V-caps and get most of the benefit of the 1800 mod for $400 in parts.
WRT the biasing issue, mine stayed steady the whole time I had them. I checked regularly and never had to adjust. A friend had the older version and did experience issues with the bias.
Great amps but like Jeffrey, I ended going the SET route.