@Uberwaltz, if you choose to pursue Ralph’s good suggestion, you can find the service manual for your deck at hifiengine.com if you register there, or if you are already registered there. It is linked to on this page:
https://www.hifiengine.com/manual_library/sony/tc-377.shtml
On page 20 of the manual (per the page numbering of the manual itself, not the page numbering of the pdf) it is indicated that R316 and R416 on the "Playback Circuit Board" adjust the maximum line level output voltages. A photo illustrates where those pots are located. There is no indication, though, of how much range those pots provide.
If your deck is presently adjusted per the procedure the maximum output voltage is 0 dbu, which is only 0.775 volts. And that is with a 100K load impedance; if you are driving a low impedance such as 10K or 20K (10K is the recommended minimum) that voltage would be a bit less.
Another possibility I thought about but rejected, btw, would be driving your amp from the deck’s headphone output, using an adapter. However while there is no indication of how much voltage the headphone output can supply, at least one of the two headphones recommended in the owner’s manual has an impedance of only 8 ohms, which I think makes it unlikely that that approach would help. If the deck were designed to drive high impedance headphones the maximum voltage of that output might have done the trick.
Best regards,
-- Al
https://www.hifiengine.com/manual_library/sony/tc-377.shtml
On page 20 of the manual (per the page numbering of the manual itself, not the page numbering of the pdf) it is indicated that R316 and R416 on the "Playback Circuit Board" adjust the maximum line level output voltages. A photo illustrates where those pots are located. There is no indication, though, of how much range those pots provide.
If your deck is presently adjusted per the procedure the maximum output voltage is 0 dbu, which is only 0.775 volts. And that is with a 100K load impedance; if you are driving a low impedance such as 10K or 20K (10K is the recommended minimum) that voltage would be a bit less.
Another possibility I thought about but rejected, btw, would be driving your amp from the deck’s headphone output, using an adapter. However while there is no indication of how much voltage the headphone output can supply, at least one of the two headphones recommended in the owner’s manual has an impedance of only 8 ohms, which I think makes it unlikely that that approach would help. If the deck were designed to drive high impedance headphones the maximum voltage of that output might have done the trick.
Best regards,
-- Al