Another thing which is important, yet I hardly ever see anyone talk about it but me, is that not only do you need to carefully level match, you also have to channel balance match. It is not uncommon for amplifiers to have a slight channel misbalance where one channel is for example .2 dB louder than the other, at least at certain settings of their analog potentiometer volume knob. Check for that.

I attempted to give a brief tutorial on how I did it when I conducted a blind test of my "expert listener" audiophile friend and actually started a thread on it at the AVS forum. Within moments of posting it a carnivore from the high-end industry swooped down to intentionally attack and sidetrack the discussion because having the lay public learn what counts and what doesn't in audio, by testing it out themselves, is completely at odds with their marketing strategy of "Trust us, we are more experienced than you and have had training to hear things you wouldn't necessarily notice until you buy an expensive, top-notch system."

New topic. Things become a bit more complex and controversial if you are attempting to level match things that fundamentally have markedly different frequency responses, such as speakers and headphones. Say for example one speaker has a stronger level of bass than the other one being tested. Do you level match them using pink noise? Do you level match them at 1 kHz? Do you instead level match them at 500Hz? Do you use a narrow band of noise centered where the ear is most sensitive, around 3.5 to 4 kHz? Do you use A-weighting when you conduct any of these level matches? You will get very different results depending one which exact method you use when the products have certain frequency response deviations between them.

I'm of the mind that one should accept that level matching things like speakers and headphones is so tricky, problematic, and questionable, that "fair, level matched comparisons" simply can't be done. This doesn't stop researchers at Harmon, etc. from publishing papers where they say "and we level matched" and nobody but me seems to blink an eye. "Our trained listeners preferred speaker A over B due to tonal balance. We level matched the two so that couldn't have influenced their selection" Um. now wait a minute. If you level matched them using A-weighting and speaker A has a broad peak at 4kHz that speaker B doesn't, I'd hardly describe the two as being "level matched" using that method because the very concept of what is "correct in all situations"  itself is nebulous and controversial.

Level matching things that generally have a flat frequency response, such as most good amplifiers, receivers, wires, and CD players is thankfully a much more straight forward process. Thank goodness! I describe the method I used at about 3m42s into this video:

https://www.youtube.com/watch?v=T_V5dPB4dYk

Another thing which is important, yet I hardly ever see anyone talk about it but me, is that not only do you need to carefully level match, you also have to channel balance match. It is not uncommon for amplifiers to have a slight channel misbalance where one channel is for example .2 dB louder than the other, at least at certain settings of their analog potentiometer volume knob. Check for that. In some instances it may be audible in lightning fast switching, like we have in a good ABX test.

What are the two UUTs or DUTs [units under test or devices under test] you wish to level match?

What device will you use for your A/B switching?

Are you testing yourself or another party?

Do you want maximum sensitivity to pick up on tiny little differences or do you have to adhere to some idiot audiophile's mythology based belief system, e.g. "switch boxes cause error so I need the cables actually swapped, instead."

Do you have a CD with test tones [probably pink noise and a 1kHz sine wave] or do you need a link to a place to download such signals?

Do you want to match levels in the acoustical domain using an expensive, high quality SPL meter or in the electrical domain using an AC voltmeter?

What device(s) will allow you to vary the level of one or both of the DUTs? is it an analog or digital control and what incremental units does it show?

Leaving my PC for some hours. Bye for now.

I agree multimeters are the way to go, but Moran and Meyer used an SPL meter so it can be done acoustically in theory. Radio Shack has a good multimter , analog for ~$25 but I have seen one at Home Depot for even less that might do. Do you have access to either store?

Please list the model numbers of the AVR and amp so I will know if they have things like trim pots, variable gain inputs, analog vs digital controls, room correction circuits, tone defeat/"pure direct" circuits, etc.

OK, now I am really gone for hours...

If your CD player doesn't have dual outs you'll need to split the one set it has with a couple of y-cords. Do you have those?

I own a Check Mate CM-140 SPL meter that has been calibrated at Cross Spectrum Labs, but I do have access to shops relatively close to me that do have volt meters. Not sure how accurate they are, though.

I think I've heard from Arnold that SPL meters can't level-match to below 0.5 dB.

Equipment for testing : Marantz SR-6008 AVR. Parasound 5250 S2 power amp. I have other equipment in other rooms, but for now I'll keep it simple.

Be warned that the Audyssey room correction doesn't actually truly turn off on the digital inputs but if you turn it off and engage "pure direct" you should be safe using the analog inputs, which is what you are doing anyways.

So even if you turn Audyssey off in the receiver setting you are saying that it's still active on the digital inputs? How do you know if its still active?

Sorry for not responding sooner, but most of this discussion is going over my head. Is a 1 kHz tone good enough to level-match electronics or is there another method that is more better or more reliable?

I would like to compare the receiver output to my power amplifier output and see if the power amp is making any sort of audible difference to the sound. Unfortunately I don't have an AB switch, and I don't want to put my system in a position that might fry the components.

If my Marantz receiver only has 0.5 dB steps, then that means I can only level-match to within 0.5 dB. Is that okay? Or should I try and match to below that? How would I go about that. Please keep in mind, I'm not a technical guy, just someone that would like to determine if any of my purchasing decisions have any merit.

Are there any places that can build or make AB switch boxes? Or ABX boxes? That would come in handy! It would be great if I could switch between components with a switch of a button.