I found this earlier today, and I was pleasantly surprised - It's a program called JCOM, developed in the early 2000s to isolate audio tracks from SPC files, the ones that SNES games use. Due to the nature of SNES tracks (each audio channel can freely switch between instruments to allow for more instruments total to be in a single track and to save space for other instruments), transcribing completely using this program takes a long time, but it's super useful for figuring out hard-to-hear chord tones and basslines.
First, you might ask, where do I download this? The answer is http://jcom.shorturl.com/
It's a pretty old site, but you can still download the program by selecting the JCOM icon on the lefthand side.
Using the program is pretty simple. You just select what file (in this case .RSN files, which are full SNES soundtracks and contain .SPCs.) using File>Playlist Editor. From there, you click "Controls" and the channel select screen is opened. When on that, you can select the channel(s) you want to record, press record and choose a directory, and then save a recording as a .WAV file where you choose. You can also adjust the panning and other stuff. Here's a demonstration of me using this:
I'm sure there might be other places to download soundtracks, but the site I use is http://snesmusic.org/v2/
I thought this would be really helpful in transcribing SNES stuff because unlike MIDIs (which are often unreliable and only based off the source material), this program helps you dissect the source material itself. In other words, you can't be wrong note-wise if you use this because you're going directly off the original song. This can save tons of time in transcribing and checking SNES sheets, and I feel it will help make our SNES sheets more accurate and faithful. The nice thing about this too is that it can't be abused like MIDIs can - any saved tracks are saved as .WAV files and therefore you still have to manually transcribe them. Copy and pasting isn't issue because you simply can't do it here. Hope this helps!
Also as an extra note, in case anyone was wondering, both sites above are completely safe. I've had no issues after downloading from either.