I'm looking for a preamp to go with my xtreme monos... it's down to a tempest (obviously a great match) or a tubed preamp. If I get the tempest, there will not be any tubes in my system and I don't like the idea of that. The tubed preamp has an input impedance of 100Kohm and an output impedance of 130 Ohm. I read in an earlier post that the input impedance of the xtreme monos is measured at 18kohm.. is this a good match?
general rule of thumb is that a preamp's output impedence should be no more than 1/10th that of the amp's input impedence. so, max output impedence of a preamp w/the xtreme would be 1.8kohms.
based on this, i would *not* use the rogue magnum 99. even tho it's rated at 150 ohms output impedence, i owned this pre, & its real-world output impedence is likely somewhere in the 2k-2.5kohm range. it would not adequately drive a 5m interconnect run into my 25kohm input-impedence marchand x-over. bass was mia, & treble was reduced. crossing the outputs w/resistors & easily hearing reduced sound level, was what gave me the actual 2k-2.5k output impedence of the rogue. (i forget which walue risistor i needed, to effect this test). the cary slp-98, which i tried after the rogue, had *no* problems whatsoever driving this load, & it was rated at 650 ohms output impedence.
there were other reasons i dint like the rogue - it was *way* coloured in sound, it was way too bloomy, it was wery microphonic. the cary slp-98, which some consider to be coloured, was wery neutral, in comparison, & a far better match to my system.
my melos music director was so much better than the cary, i stopped looking for preamps...
it's presently being traded for another single-ended music director (mine's balanced, & i don't need that feature), that has a $700 tubed wolume control mod & three more line inputs. i can't wait! the tubed wolume pot is supposed to be even more transparent than their famed (but unreliable) photentiometer.
doug s.
