preamp outs to headphones

[Bugler]

I have a dual zone preamp (Carver C-5) and am wondering about driving some simple headphones directly off the zone 2 preouts. There is no headphone jack for zone 2. It sounds ok to me. It doesn't go as loud as if plugged in to zone 1 headphone jack but it's acceptable. I have Sennheiser HD280 Pro, Bose Tri-port TP-1A and a couple Koss & Sony phones.
Thx

 

[audiomagnate]

If there is a gross impedance mismatch you will hear it, so it must be fine, except for the limited level.