Hello submariner, and welcome to thecarversite.com. We're glad you're hear. There is a lot of information here, much technical know how, and a pretty good bunch of folks that are happy to help.
I have a 4000t and a C-1 that have both been serviced and upgraded. The 4000t is a later iteration of the C-4000, and my C-1 has the BillD modification. I love them both. Placing either of them in my main 2 channel rig is the right choice. The 4000t is paired with a M500t mkII, and the result is phenomenal. The BillD c-1 is paired with a M1.0t and the result is phenomenal.
Once you get to Novice status, please consider uploading some pics of your gear in the Members Systems area. We all like pics of all kinds of audio gear.
In the meantime, kick your shoes off, turn up the music, and welcome aboard.