I might be buying the eclipse HU but the new range have amp built in. I don't need it anyway. I have heard the 9815 with power IC on and off make an obvious different. I think this may workout the same way too but require it to physically disconnected. In theory the power supply will be more stable due to less load which will then translate to less harshness and better focus.

How to actually locate the power IC in a HU?

it'll be attached to the HU housing using it as a heatsink...

Less load? What load? If there's nothing connected there's no load. If there's no load then there won't be 'more focus', 'less harshness', or any of those other things. Don't go messing around inside the source unit in an attempt to fix something that isn't broken - especially if it could cause damage...

I mean less load to the power supply. If the unit need less power to run them the power delivery will be more stable.

The difference will only be the idle current, and that isn't really that much. It won't make much difference to the stability of the power supply.

that's what I would've thought!

If that is the case anyone could give me explanation of why 9815 sounded much better when power IC are off?

very true. 9815 sounds so much better when it off. Mr Bob too should know that.

maybe turning off the IC also turns off some other form of processing being done behind the scenes (and encourages you to buy more amps :tony:) I dunno i've never turned mine on lol

can't say i've ever compared it with the IC on,
i don't need it so it stays off, i do it mainly to keep the HU cool. it seems to get warm when it's switched on, even if it's not being used.

Turning the internal amplifier off on my headunit doesn't make any difference to the SQ either...

BassA, what front end are you running?

e,g, if it's sony coax's then i wouldn't expect a gain, but if it's a high end front stage, then it's a bit different.

Last time I played with that setting and the others in that menu was actually a few years ago, when I first got it, before I had my front speakers installed (all I had was large holes in the kick panels LOL). At the time, I had it (jvc sh-77r) hooked up to my Pioneer home amp and trusty bookshelf speakers. I remember, because at the time I really thought it would at least make some sort of difference, but it didn't make any noticeable difference at all...

When I get my new front stage, I'd have to find the manual again if I was to remember how to get to those settings again before I could actually test it. My current temp front stage is kind of mix and match at the moment..

so by your own admission, you don't think that your setup was suitable for making an accurate comparison?

To be honest, obviously turning the amp off/on in the headunit changes the processing.... There's no iff's or buts about it, the internal amp may produce heat (they usually do) even if unused, but they draw MINIMAL power, it's enough to make it hot (in the case of the Nak CD-45z - nearly hot enough to melt cd's!) but with no load, it means no output which means no major current drain.... even 200ma can create alot of heat....
I'm not saying it doesn't change the CDA-9815 - what i'm saying is it shouldn't change ANYTHING with the headunit... Disconnecting the internal amp physically is a very bad idea, because they are usually "flat pack" "all in one" devices that will also do voltage regulating for, say, the cd player (not sure what parts exactly, but they do do it)... When you switch off the one in the CDA-9815 - it would only disable the power amp itself and create a by-pass for the pre-outs... Normally, in a well designed unit (without that feature) it wouldn't change a thing..... Hell the Nak CD-45z sounds bloody good with it running....
If you get my point!

Actually, I believe it was suitable, because I was VERY familiar with it at the time, as I was writing/producing music with those speakers back then.

OK I just place my order the HU in question will give you a result after I have it all done.