hey all picking out a tube pre for my cousin, after ruling out the manley, and drawmer tube offerings, i'm pitting these two against each other in this slow narrowing of tube pre's. this will likely go alongside an api 512c and 550b. the obvious differences are one is a rackmount psuedo channel strip the other is a 500 series pre. they both have in/out trannys (un-named in the UA, jensen/cinemag in the 583s) something i found interesting was the use of two tubes in the 'two input stages' of the 610, and the use of an output tube (which on the la-610, is moved to the output stage of the compressor) my impressions (from what i could gather from online demos/reviews) is that the 610 has a more dark old kinda sound. having heard a recording done w/ the la-610 down at the studio it seemed relatively full, but w/ a modern yet smooth high end. the 583e sounded pretty f' in wild on the demos, full and saturated, but kinda scratchy (which very well could be the amp settings which usually had a ton of presence, and a fair amount of highs) on the soundpure LaChapell Audio 583s Tube Preamplifier | Soundpure.com demo. oddly enough i couldn't find any examples of a mic'd up rock guitar for the la-610, mostly bass and vocals.... Getting Hands-On with the Popular LA-610 MkII Classic Tube Channel Strip - Blog - Universal Audio so my impression so far is that the 583s sounds more like the amp does in person, while the UA tends to have a more smoothing quality. any thoughts on these? suggestions? other units that compare favorably? thank you!