JaZZ
Headphoneus Supremus
I've tried out the Earmax Pro and the Corda Blue with my Metaxas Solitaire power amp: Both were working fine – so all headamps seem to be adequate preamps. Actually no surprise if you remember the electrical conditions: the source signal is amplified to a sufficient level, and the output impedance is in each case far below any critical value...
Only handicaps: just one input and the headphone-dedicated output jack. But there are adapters. If you can handle the lack of comfort, headamps probably offer better sound for the money than full-blown preamps.
In many cases the source signal is even strong enough to drive a power amp directly. If the source output impedance is low (<800 Ohm) and at the same time the power amp's input impedance at least 20 kOhm, a 10 kOhm potentiometer will adequately attenuate the signal. Provided that the cable isn't too long and its capacity isn't too high, thus the source signal arrives the power amp virtually unaltered – in contrast to any preamp, even the world's best.
JaZZ
Only handicaps: just one input and the headphone-dedicated output jack. But there are adapters. If you can handle the lack of comfort, headamps probably offer better sound for the money than full-blown preamps.
In many cases the source signal is even strong enough to drive a power amp directly. If the source output impedance is low (<800 Ohm) and at the same time the power amp's input impedance at least 20 kOhm, a 10 kOhm potentiometer will adequately attenuate the signal. Provided that the cable isn't too long and its capacity isn't too high, thus the source signal arrives the power amp virtually unaltered – in contrast to any preamp, even the world's best.