Originally Posted by moonhawk
Unless you're planning on blasting a lot louder than you were with your 7009 before, the A21should make little to no difference in your current draw. The extra power is there for headroom for loud peaks, etc.
By pre-outs, you do mean pre-amp level outputs, right, with the volume controlled by the SR7009?
In which case, you're fine.
Just go ahead and fire it up already--it isn't all that delicate, and we want to know how you like it.
just coming back to this...I did just that, and included my first impressions below...I used the "pre out" RCA connections from the back of the sr7009, labeled front right and left which is in the same "section" of connections as the subwoofer outputs which leads me to believe that is the correct way to hook up the A21.
I bypassed the gain controls by turning them up all the way to THX ultra certified level recommended in the setup manual which bypasses these controls letting the sr7009 handle the volume adjustments.
First impressions are key they say....although most products I have come across these days have a "break in" period of listening hours that is mentioned in the user manual upon unboxing, I thought the A21 performed brilliant from the very first session. I have only about 6 hours of listen time so far, but I haven't found a volume level yet where (with or without room eq) where the A21 does not outshine the sr7009. I had the expectation it would, but it was reassuring immediately to hear the difference in sound coming from the CM10s that didn't just sound louder to my ears but it seemed to install a certain level of confidence these speakers never had with the sr7009. The cm10s sound fine hooked up with the sr7009 and I plan to do more switching to see what i think of all the differences but the A21 really seemed to bring them out of their shell for lack of a better phrase. If the CM10s could possibly be "tired" to the ears after awhile playing back from my AVR (which I never thought they did" the best description I have for the A21 to try and compare is "breathed new life into them"
So all gushing aside - I love it so far. If I had to pinpoint how the A21 sounds "better" to me is in the midrange and lower frequencies where it seems to just drive the speakers as a whole better than my reciever. There was an almost forward sounding punch, that did not degrade the sound of the CM10s but it was like the A21 is more eager to drive the speakers than my reciever, almost like it was getting ahead of the other speakers when I did the room eq and took notice of the difference in sound to the chirps coming out of each speaker. I suspect this could be related to the class A amp always running with a bit of line voltage at all times. If I listen closely to the speakers after running it for about an hour (I have not tested using the ground lift yet) there is definitely a noticeable hum but it becomes inaudible to me once any level of music is being played back. I like to think of it like the A21 is a 12 cylinder, muscle car of an amp that idles along at a very low RPM until called by the sr7009 (the throttle if you will) to "go".
The far and away best attribute of this amp (in my opinion) is what it sounds like listening at lower levels. I had inquired about this perception by some and disbelief by others that a power amplifier (or simply a significant increase in power available to the speakers) will sound better at lower volume levels but I can't remember the technical explanation behind it. All I can say is it seems to add what I thought I was "missing" but had trouble explaining in forums from the cm10s when I ran them from the sr7009. My guess is this is due to being in class A mode at low levels before switching to AB, which I understand happens somewhere around the 7-10 WPC level (i think?) which would lead me to believe that with less than 10 WPC being delivered to the cm10s they had a full, rich, and almost loud (not a good descriptor here) sounds that made some night time listening much more pleasurable. which would make sense based on many of you telling me in the past that having more "power" was not necessary at my listening levels
more experimentation to come but overall it is too early for a verdict on the purchase but so far the amp has met or exceeded my expectations based on some limited research and very limited knowledge of what benefit I would get or hear when adding the amp into my setup.
I find the A21 runs very cool so far on the bottom of my rack (it sits on glass right now and the shelf above it has been removed) where I have teh sr70o9 and ud7007 as well spaced with one shelf in between each to aid in ventilation. the sr7009 seems to still run fairly warm but by no means overheating.