Luis,
The TX-601 arrived and I had a chance to do some minor testing. Bear in mind that anythings an improvement over my old Pioneer pro logic receiver. That said, I'm amazed at the detail and clarity of 601's projected sound with CD music and DVD sound tracks.
(Open Range DVD). Receiver was in the wrong mode during setup. Entered the correct mode, (5.1 for my setup) in the middle of a gun fight. Bass was crisp and tight yet still high enough to localize. I've been around lots of gun fire and an here to tell you the shots sounded so real I jumped out of my seat when the 1st one went off. Now convinced that the 10" woofers provide all the base I'll need. Surround sound was crisp and detailed once properly dialed in using the on screen speaker setup. IMHO, this is a must have feature as it lets you customize the sound to match your speaker set up. My tiny rears are wall mounted 14 feet from my main seats and need all the boost they can get. I could actually hear the rears drop off at the designated distances as I played with the distance controls. Center channel sound sux; need a new speaker.
(CD Robert Cray Sweet Potato Pie) Young Bob never sounded better! Until last night I always thought of Cray as an exceptional guitar player with a decent voice. I was blown away by the raw emotion and feelings projected by his voice. Clearly heard, (for the first time) the drummer lightly tapping his' drum sticks together at the right rear of the sound stage.
(CD New World Symphony 4th movement) Decent soundstage, was able to clearly locate all of the instruments. However, (perhaps owing to the limitations of my speakers) depth was rather shallow, as if the entire orchestra was only 3-4 layers deep. If others who describe the Onkyo sound as "bright" mean 'in your face', then I have to agree. The horns which dominate the movement re verb to the point of sounding omni-directional.
(CD Sting Fragile) Mandolin, (or at least I think it is) is very clear precise and omni-directional. At the same time I swear you could reach out and touch Sting about 6" above center stage. His' voice is so clear that, what I once thought was a cool way pronouncing words that end with S, now seems more like a minor speech problem.
As for volume and distortion, lets just say at the high end my ears were hurting before distortion became an issue.
Sorry, can't give you more info on controls and features at this early stage of the game. Anyway, this is all IMH and untrained opinion, so take it w/ a grain of salt. I'm sure you'll be happy regardless of which unit you select. Happy hunting!