I have been using a Reference Line Preeminance 1A passive preamp for the last two years. I find that recessed treble and listener fatigue comes primarily from poor recordings.
The passive to my ears lets everything through as recorded. It has meant that some CD's sit on the shelf because the recording values suck.
The passive to my ears lets everything through as recorded. It has meant that some CD's sit on the shelf because the recording values suck.