Difference between Luxman L-550A II & L-507u

No worries Nolitan. I really think the 505 is great. You should also know that the difference between the 505 and 507 isn't just 10 watts. The 507 has better binding posts (look like WBT in picture, the newer distortion reduction circuit (ODNF 3.0 vs. 2.2, and another set of balanced inputs. Not saying that alone makes it worth the jump, but it is more than just a conservatively rated 10 W jump.

Who knows if 507u is closer to 509u or 505u in performance...

507u is quite a big jump from 505u in terms of driving capability, clarity, depth of the stage and the overall smoothness. my local dealer here have all 505u,507u,509u, and 590A II in demo. i was lucky to have a chance to do a/b/c/d/e comparison with all of them along with a gryphon diablo. before i went there i was targeted at 507u simply because i thought it has newer circuit board, only 10w difference with 509u and it's 2.5k cheaper. the speaker was a pair of triangle megallen bookshelf, cdp was a luxman d-08. i first listened to 507u and overall i was quite satified though i found it was a little too ss sounding for me. switched to 590A II, 590AII had a lot more body and weight in the sound nodes, its definitely a thick sounding and musical amp. the 507u did better on high/low extension but could not match the well defined sound nodes and smooth presentation of the 590AII.

and then i switched to 509u, i was confident to say 509u was in complete different class with 507u and 590AII. it had the smoothness and body just like 590AII with just a tad thinner sounding. soundstage was so open with a lot more depth, what i liked the most was the authorities and powerful control of the entire frequency spectrum that you could not find in 507u and 590AII. 509u was able to portrait a complete stage while listening to orchestra. high/low extension was extremely well and stable.

i finally bought 509u even though that was out of my budget but at the same time it did so well that was beyond my expectation and now i couldn't be happier. i compared it with gryphon diable and i would say they were in the same class. gryphon had more powerful bass and sedutive vocal, however, it lacked depth, sound seperation was even worse than 507u and highs/details was not so great at all

Oh wow, nice comparo!! thanks!! 509u is a bit out of my range.

Anyone hear or try the 550A with the Harbeth M-40.1's? I'm thinking a 20WPC integrated, albeit conservatively rated, would have a tough time pushing 40.1's 12" woofers.