I built one with the signature upgrade. I am not by any means an electrical hobbiest but I had a great time and the directions are excellent. I used GR Research speakers with the amp and the sound was fantastic. At the time I also had Martin Logan reQuests with Adcom electronics and when I compared the two systems I was shocked at how good acoustic music and vocals were compared to the ML/Adcom combo. I ultimately sold the Assemblage because the exposed tubes were a bit risky in my environment but I miss the golden glow of those big 300's. As a bonus, the "sweat factor" of building it myself clearly added to the musical enjoyment. To answer your specific question my tubes weren't broken--however, the AC choke was buzzing and when I called about it the guy that designed the amp picked up the phone and sent me a replacement immediately. Great service! Feel free to email me if you have any questions.
