I have a GNSC Reference Opus 21 and have owned Opus 21s in both stock and GNSC Reference modification versions. The GNSC mods seemed to give the greatest impact in the areas of bass weight and depth and overall dynamics. As others have commented, the Opus 21 is a great product stock but is improved by GNSC modifications.
I think that Opus 21s have become available more frequently on Audiogon during recent months and prices seem extremely reasonable for the quality of product you get. While I understand that the new Resolution Audio music center/CD player will be a significant improvement upon the Opus 21, the current prices of both new and used Opus 21s make them very attractive.
I have only spoken to Jeff Kalt once or twice and he was as advertised above, a great guy. I have more extensively dealt with GNSC and Steve Huntley. Steve is unsurpassed as a dealer and modifier. So, while we should focus most on the sound of a component, the fact of the matter is that our enjoyment of a component derives from the entire ownership experience. You can't go wrong dealing with either of these guys.
I think that Opus 21s have become available more frequently on Audiogon during recent months and prices seem extremely reasonable for the quality of product you get. While I understand that the new Resolution Audio music center/CD player will be a significant improvement upon the Opus 21, the current prices of both new and used Opus 21s make them very attractive.
I have only spoken to Jeff Kalt once or twice and he was as advertised above, a great guy. I have more extensively dealt with GNSC and Steve Huntley. Steve is unsurpassed as a dealer and modifier. So, while we should focus most on the sound of a component, the fact of the matter is that our enjoyment of a component derives from the entire ownership experience. You can't go wrong dealing with either of these guys.