What to replace CAL ALPHA dac

Stay with the Cal, one of which I have and still enjoy. I have other players, hi end Sony (5800) and Oppo (105), but still feel the Cal has great sound and a warmth, which current DAC's miss. I suggest upgrade of the tubes of the CAL might be a better step.

Agree with Buconero. Hard to beat in your budget unless you are prepared to have a SS DAC. The type of tubes you use in this unit can produce a wide range of tonal response. If you like 'warm' try some JJ ECC 83's. Since there are only 2 of them, splurge on the 'gold pin' edition. FWIW, if you are up to ss sound the Marantz 8004 is not only very good it is also a CDP and has input from other digital sources. It has gotten good reviews.

"The type of tubes you use in this unit can produce a wide range of tonal response."

The bias is set for the original tube and is not user adjustable. The original tube will usually give the most neutral sound. If my memory serves me well the Delta, in its original form, is already on the warm side. The transport makes a big difference on this one.

Rrog, What was the 'original' tube? Mine came with X brand 12AX7A's which is essentially the same tube I recommended is it not? The manual did not designate which brand of tube to use.

FWIW, while I agree with you regarding the warmth of the Delta (an ideal transport for the Alpha I think) I used a different transport for a number of years and in my system then a little added warmth was a good thing. Perhaps IF the OP is using a Delta he might not need more warmth, but I inferred from his post that he did not use a Delta.