Usually the best way to run an headphone amp off a preamp is to put it on the tape or processor loop out. That way, it is in no way keyed to the volume pot on the preamp and you only have one volume pot in the circuit to potentially muck with the sound (the one on the headphone amp). The second main outputs on a preamp are just that, and they're intended to run to an amp -- mostly useful if you're biamping. Most "headphone amps" are indeed mini integrated amps -- they've got an amplification section and a volume pot (some, like some of the Headroom amps, will actually have a main out and can be used as a single source preamp in addition to a headphone amp). I'm beginning to confuse myself. Let's regroup.
Yes. You can certainly run a headphone amp off of the second main output on a preamp. It is somewhat less than ideal due to the fact that, as I tried to explain, this puts the volume control from the preamp as well as the volume control from the headphone amp both in the circuit. The more you attenuate or amplify the signal through a volume control, the more opportunities you have to potentially degrade the sound. If you use the tape loop, you've only got one volume control. If you use the second main out, you have two. It'll work fine, but, if you have a tape loop that isn't busy already, I'd use that first. If you use the main out, you may want to experiment a bit. It could be that the best sound comes from dialing in the preamp to 0 gain (where it is neither attenuating nor amplifying the signal from the source) and then controlling the volume for the cans from the headphone amp. Trouble with this is 1) who'se to say where 0 gain is (although it's likely someplace generally between 12 and 2 on the volume knob) and 2) if you happen to turn on you amp at that volume, it'll be alarmingly loud in a big hurry.
Reason I've prattled on about this is that I've recently switched out my preamp with one that doesn't have a tape loop and have spent some time wondering this one myself recently. The tape loop route for the headphone amp works great, but since I've reworked things (now have the headphone amp hooked up the the second main outs on the new preamp) I haven't had a chance to listen to the cans yet. Maybe I should do that before I go on like this....
As for amps, I got a Headroom about four years ago and really don't know what's out there these days. I like the Headroom, though.
Yes. You can certainly run a headphone amp off of the second main output on a preamp. It is somewhat less than ideal due to the fact that, as I tried to explain, this puts the volume control from the preamp as well as the volume control from the headphone amp both in the circuit. The more you attenuate or amplify the signal through a volume control, the more opportunities you have to potentially degrade the sound. If you use the tape loop, you've only got one volume control. If you use the second main out, you have two. It'll work fine, but, if you have a tape loop that isn't busy already, I'd use that first. If you use the main out, you may want to experiment a bit. It could be that the best sound comes from dialing in the preamp to 0 gain (where it is neither attenuating nor amplifying the signal from the source) and then controlling the volume for the cans from the headphone amp. Trouble with this is 1) who'se to say where 0 gain is (although it's likely someplace generally between 12 and 2 on the volume knob) and 2) if you happen to turn on you amp at that volume, it'll be alarmingly loud in a big hurry.
Reason I've prattled on about this is that I've recently switched out my preamp with one that doesn't have a tape loop and have spent some time wondering this one myself recently. The tape loop route for the headphone amp works great, but since I've reworked things (now have the headphone amp hooked up the the second main outs on the new preamp) I haven't had a chance to listen to the cans yet. Maybe I should do that before I go on like this....
As for amps, I got a Headroom about four years ago and really don't know what's out there these days. I like the Headroom, though.