Thanks' to everyone for their responses. In answer to some of the questions from above:
Yes, I am using the Herron MC Phono-pre. I had it set-up at the factory to match the recommended loading of the Karat cart. at 100 Ohms. In discussions with Kieth Herron regarding my wish for more volume, he suggested I clip the leads to the resistors which gave me about 6db and un-loaded the cart. Truthfully, the volume is very close to being acceptable now, but I prefered the sound with the cart. loaded. The mids and highs lost some extension and sweetness, solo strings do not have the immediacy they had.
My Pre-amp is a Mark Levinson 380S, which if I remember correctly, adds about 17db gain. My digital front end plays at a reading of 55 to 58db on the 380S, my Rega P-25 through the Herron, plays at 65 to 68db on the 380S, to get the same perceived volume and detail. Unfortunately, I start getting noticable background noise from the Herron at a reading of 60db (lower starting point and louder noise from the Coph Nia and Rega Fono). From that, I have concluded that I need a boost of at least 10db.
Yes, I am using balanced interconnects between the 380S and my amp, and the P-25 is isolated. FWIW, I get no background noise from the digital front end (Levinson 37 Transport and Chord DAC 64) when played at any level.
From the responses above (and I really appreciate your help!) it looks like my choices are 1) get a good transformer at +$1K; 2) get a higher out-put cart for the same or more $'s; or 3) re-solder the resistors and live with the noise (least acceptable alternative).
Thanks for everything, David.
