Hi everyone.. Im on the lookout for a pre amp. What the heck are the differences (apart from tone controls/ no tone controls, phono, remote or not, facia finish) of all the rotel pre amps I've been sifting through on the 'Bay? Im talking RC 850, 860, 971, 972, 980..etc etc. the choice seems to go on and on (and the weight differences are dramatic too- 3kg to around 5kg. The specs on hifi engine talk about some slight frequency differences but as a beginner I can't spot much else.
I want a phono. Not fussed about remote (that much) or age. Going to use it to run 2 rotel rb 970's in bridged mode. As Used pre's, most of these seem to command a similar price.
Is there anything I should avoid in this series and anything I should go for? ( I have considered the ra series and just use the pre out.. but they look 'cheaper' )
Any pointers would be appreciated!

( I have missed a couple of decent adcoms and have seen a David hafler but not a clue whether these are worth a punt over the rotels).