I'm glad you ordered tubes, that is what you need to do, start somewhere. You never explained what you wanted from the stock sound, and what you were hoping to gain. As stated above the Mullard CV 4004 is an excellent choice, but I am on the opposite view, I prefere the lusher Mullard 10M gold pin (or any Mullard 12AX7 gold pin tube from the '60's. I used the 10M myself.
In the 6922 I went through many tubes, and eventually found a quit non microphonic pair of '50's Amperex pinched waist that are perfect matches with the 10M. The issue is in today's market that is $1000 plus dollars for four tubes, if you can find quit ones. There is some real question if $1000 in tubes in a $4500 component is even logical, but in my mind it made the Calypso a remarkable unit.
BTW, I kept mine in the high gain and it was dead quit. Also last year I upgraded to the Callisto, many more tube variables to deal with.
jd
In the 6922 I went through many tubes, and eventually found a quit non microphonic pair of '50's Amperex pinched waist that are perfect matches with the 10M. The issue is in today's market that is $1000 plus dollars for four tubes, if you can find quit ones. There is some real question if $1000 in tubes in a $4500 component is even logical, but in my mind it made the Calypso a remarkable unit.
BTW, I kept mine in the high gain and it was dead quit. Also last year I upgraded to the Callisto, many more tube variables to deal with.
jd