Picture of Krell Showcase preamp rear
I do not think you want to click on "tape monitor" because that will route the "tape in" to the system. When set to "source," the tape out - in your case, your headphone preamp - should receive the output of whatever other input is selected.
The tape monitor function is really intended to use with a three-head tape deck, allowing monitoring of a signal just after it has been recorded.
I did try connecting the headphone amp to the preamp L-R output jacks. Still not working.
I'm not sure you understand how this should work. Or, maybe I'm not understanding you properly.
The headphone preamp input should be connected to the Krell's "tape out" jacks. Whatever source is selected on the Krell should then go the the headphone preamp - but do not select "tape monitor" on the Krell. That should be left on "source."
Please try that and report back.
My 4K player only as HDMI out, Coax out. No analog out.
I would like to use my headphones with my CD player too, so I do not want to tap directly from 1 source and always have to switch cables between the CD and 4K.
I emailed Krell tech support today. Maybe they will have advice, not counting on it. I’ve never contacted them before.