Jeff Rowland amp owners: What's your pre-amp??

Responses will depend upon which Rowland amp you have.

Early Rowland amps used the 600 Ohm balanced input impedence standard and won't work well with some tube preamps.

The 6/8ti/9ti, the 10/12, and the 300 series amps are transparent and resolving -- they demand quality preamplification. These amps are fully differential balanced and benefit from a balanced preamp (that's one reason the top ARC amps work well with them).

The 201/501's are more forgiving of partner components.

I used two single-ended preamps with Model 6's, a Hovland with the amp switched to the higher impedence setting (18 Khz.), and an ARC LS-3, with the impedence set to the standard 600 Ohms. Both set ups were great.

Yes, 32K or 40K settings should be more than enough in most cases.

While these are just general guidlines, try to avoid a match between an amp and preamp where the preamp has 1/10th or less output impedence compared to the amp's input impedence. For example, some tube pre's have an average output impedence of 1,400 Ohms or so. Using the one-to-ten ratio, you would thus not want to pair it with an amp having an input impedence of less than 14,000 Ohms (many solid-state models do).

There will be either factors you need to check for, like appropriate preamp gain to get desirable levels of volume from a given amp, and amp sensitivity, which is the flip side of the preamp gain preoccupation. In general, you want to avoid amps with unusually high sensitivity, as most preamps will make them go very loud with only a few clicks on the volume control, thereby giving you only large gradations in loudness from soft to loud. Of course, you want to be wary of preamps with really high output (the CAT amps), as they for their part can drive a moderately efficient amp into clipping with juts a few turns of the volume control, the same lack of play in the volume control being the issue.