Sand Man:
My only hesitation about a tube preamp is what I previously mentioned, which is to say, the inability of many of them to drive long runs of cable and impedance mismatches with amps (this is mostly a problem when they are paired with solid-state amps, which tend to have much lower input impedances than tube amps). The ARC LS-5 Mk. III has a fairly low output impedance for a tube preamp at 400 Ohms on average and the specs indicate it will work with an amp having a minimum input impedance of 20,000 Ohms. However, the impedance likely rises in the bass. The Model 6 provides a choice of 600 Ohms or 18,000 Ohms input impedance. Especially with long interconnects, there is a chance that you could experience some bass rolloff. This is not a reflection of a lack of quality -- some really high-end balanced tube preamps, like the Audio Research Reference 3 and BAT 52, are worse. Regarding the Audio Research Reference 3, John Atkinson wrote:
"The output impedance was also to spec., at 635 ohms balanced and 326 ohms unbalanced in the treble and midrange, but rose to 1437 ohms and 625 ohms, respectively, at 20Hz. This rise in source impedance rolled off low frequencies a little early into the punishing 600 ohm load (fig.1, bottom pair of traces), with a 3dB frequency of 17Hz. As this is a relatively low frequency and the preamplifier will never be used with a power amplifier having an input impedance as low as 600 ohms, this rise in source impedance will not be a factor in practical use."
In fact, Rowland amps have impedances typically seen on pro gear and you can in fact choose a 600 Ohms input impedance setting (which would work best with a Rowland preamp). The Rowland Synergy IIi, preamp, for example, has a balanced output impedance of 80 Ohms -- it will drive anything.
While you would likely be fine with the LS-5 on the Model 6's (set at 18,000 Ohms input, of course) and I would try it if I were you unless you have really long runs to your amps, the Synergy IIi is a risk-free choice.
My only hesitation about a tube preamp is what I previously mentioned, which is to say, the inability of many of them to drive long runs of cable and impedance mismatches with amps (this is mostly a problem when they are paired with solid-state amps, which tend to have much lower input impedances than tube amps). The ARC LS-5 Mk. III has a fairly low output impedance for a tube preamp at 400 Ohms on average and the specs indicate it will work with an amp having a minimum input impedance of 20,000 Ohms. However, the impedance likely rises in the bass. The Model 6 provides a choice of 600 Ohms or 18,000 Ohms input impedance. Especially with long interconnects, there is a chance that you could experience some bass rolloff. This is not a reflection of a lack of quality -- some really high-end balanced tube preamps, like the Audio Research Reference 3 and BAT 52, are worse. Regarding the Audio Research Reference 3, John Atkinson wrote:
"The output impedance was also to spec., at 635 ohms balanced and 326 ohms unbalanced in the treble and midrange, but rose to 1437 ohms and 625 ohms, respectively, at 20Hz. This rise in source impedance rolled off low frequencies a little early into the punishing 600 ohm load (fig.1, bottom pair of traces), with a 3dB frequency of 17Hz. As this is a relatively low frequency and the preamplifier will never be used with a power amplifier having an input impedance as low as 600 ohms, this rise in source impedance will not be a factor in practical use."
In fact, Rowland amps have impedances typically seen on pro gear and you can in fact choose a 600 Ohms input impedance setting (which would work best with a Rowland preamp). The Rowland Synergy IIi, preamp, for example, has a balanced output impedance of 80 Ohms -- it will drive anything.
While you would likely be fine with the LS-5 on the Model 6's (set at 18,000 Ohms input, of course) and I would try it if I were you unless you have really long runs to your amps, the Synergy IIi is a risk-free choice.