I was and still am a huge fan of the Opus 21, I owned it for about 4 years, loved it. I did want something more though and here is what I found to surpass it. Of course, if you like the BB1704 chips I was not able to find any other unit that had other chips that I liked better.
Wadia uses the 1704s, any of the higher Wadias will do it, The Esoteric D70 is essentially the ultimate expression of the 1704 chip, I own it now and doubt I can find something that is better. The Esoteric D05 is better, but still missing some of that organic nature I get from the 1704s. The Esoteric X03 is also better, all in one box but no digital input, it has 1704s as well. I suggest a D70 and a Krell 300CD as a transport. Pick a Krell with one of the Teac transports, not the philips ones. Other transports include Vecteur D2, there are a lot of others to choose from. You could also use a PC as a transport. That is a whole other topic.
Wadia uses the 1704s, any of the higher Wadias will do it, The Esoteric D70 is essentially the ultimate expression of the 1704 chip, I own it now and doubt I can find something that is better. The Esoteric D05 is better, but still missing some of that organic nature I get from the 1704s. The Esoteric X03 is also better, all in one box but no digital input, it has 1704s as well. I suggest a D70 and a Krell 300CD as a transport. Pick a Krell with one of the Teac transports, not the philips ones. Other transports include Vecteur D2, there are a lot of others to choose from. You could also use a PC as a transport. That is a whole other topic.