Send me the exact circuit with idss values you got and drain to earth voltages you can measure to see if we can easily convert it to 60dB with not much hassle first.
OK then. Before we perplex it with extra Jfets or whatever, short each R2 with a parallel jumper wire, parallel 220R to each R6, and go 40V B+ on both channels. That will boost the gain to about +2.5dB without any real hassle. Lets see, maybe it will do the trick. Its like your cart becomes 0.53mV with the gain you now got. About +30% on line output. Is there gain in your preamp by the way? 63dB is for 0.2mV LowMC carts usually.
I meant in your line preamp. Is there gain in it, or is it a buffer? Also what is the voltage gain of your power amp and the speakers sensitivity? Listening distance?
I am listening from Densen dm10 integrated amplifier (2 X75W) and Audio Phisic Tempo III 92db. The distance is about 2.5 m.
That one had tape input, should be content with 250-350mV. Try the easy +30% phono output boost we discussed first.
Edit: Found its manual. Today you have around 250mVRMS at 0db disc modulation phono output with your cart, tomorrow with the changes you are going to have around 330mV. Should cover.
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I check gain, bias, and Riaa curve on the simulator after I adjust the Beta and Vpinch on the Jfet model. Those voltages and currents he had given for his 56dB in the previous page, follow exactly for instance, so I am confident on what to adjust given the query.
