My main suggestion is that you rule out any candidates that are not fully balanced designs. Besides the usual advantages of fully balanced architecture, and the fact that the Spectral amp is fully balanced, I say that because like probably all Spectral products the DMA180 has ultra-wide bandwidth.
Which means that keeping ultrasonic nasties such as digital noise from coupling onto the signals that are sent into it will probably assume greater significance than with amps that have more conventional narrower bandwidths. The common mode noise rejection of balanced interfaces will certainly be helpful in that regard, and with a very high quality system such as yours it would not make sense to use a component with balanced interfaces and an unbalanced internal signal path.
And if you end up looking for a tie-breaker between preamp candidates, my instinct would be to go for one with narrower bandwidth, say 100kHz, rather than the Karan's 300kHz rating, or other preamps that have even wider bandwidths. Again, to minimize the possibility that high frequency garbage will find its way into the power amp.
A case could perhaps be made in the opposite direction, that you want a very wide bandwidth preamp to maintain an overall system bandwidth consistent with the Spectral's, but in so doing your system would become wide open to the effects of radio frequency and/or digital noise that may be present, with little or no advantage as I see it.
Regards,
-- Al
Which means that keeping ultrasonic nasties such as digital noise from coupling onto the signals that are sent into it will probably assume greater significance than with amps that have more conventional narrower bandwidths. The common mode noise rejection of balanced interfaces will certainly be helpful in that regard, and with a very high quality system such as yours it would not make sense to use a component with balanced interfaces and an unbalanced internal signal path.
And if you end up looking for a tie-breaker between preamp candidates, my instinct would be to go for one with narrower bandwidth, say 100kHz, rather than the Karan's 300kHz rating, or other preamps that have even wider bandwidths. Again, to minimize the possibility that high frequency garbage will find its way into the power amp.
A case could perhaps be made in the opposite direction, that you want a very wide bandwidth preamp to maintain an overall system bandwidth consistent with the Spectral's, but in so doing your system would become wide open to the effects of radio frequency and/or digital noise that may be present, with little or no advantage as I see it.
Regards,
-- Al