Not sure if it's the same with the SC-88, but for the SC-88 Pro, selecting the SC-55 map is not enough to get the same sound, as that only maps the instruments like the SC-55, but that's not really important, as it doesn't affect the 128 GM instruments anyway. Audible differences in GM are only due to other parameters changed as well.

To get the same sound as an SC-55, you must enable SC-55 compatibility mode. I've posted the infos on how to do that here.

Everything I've read suggests that the SC-88 and SC-88Pro sound the same in SC-55 mode, and neither is accurate as they use a different (updated) synth engine. They also both have the same output circuitry thus sound the same quality-wise.
The SC-88Pro basically supports more effects, had more ROM for added instruments.

derSammler wrote:

To get the same sound as an SC-55, you must enable SC-55 compatibility mode. I've posted the infos on how to do that here.

In my testing, switching the SC-88 Pro to SC-88 compatibility mode w/ the SC-55 map doesn't make it sound like a real SC-55. It just sounds like an SC-88 with the SC-55 map.

My benchmark for this is the Doom menu music. On a real SC-55 there is a distinct filter-sweep synthesizer sound. On the SC-88 or 88 Pro (regardless of mode/map), it sounds different.

Same thing can be heard in the Descent level 1 music.

mdfrankaudio wrote:

Does the SC-88 sound *exactly* like a SC-55mkII in this mode?

I can't speak for the Mk II, but in comparing the SC-55 Mk I with the SC-88 w/ the SC-55 mapping, they don't sound identical. They're close, but definitely not identical.

They don't sound the same.
The SC-88 on the "SC-55 MAP" has more than a few sounds taken from the SC-88, most popular is the kick drum and ride cymbal in Duke3D track, but there are more.

Listen here for Duke3D Intro track.
http://www.wavetable.nl/category/comparisons/

Speaking of the SC-55, (mk I unit) for the best DOS retro western game compatibility (eg: Sierra, Lucasarts, Dynamix) is there a difference between units with ROM versions 1.2x and 2.00?
I know for a fact that they all have a GM mode (not selectable like on mkII units) but what's not clear is if the infamous Capital Tone Fallback is supported on ROM version 2.00.

James-F wrote:

They don't sound the same. The SC-88 on the "SC-55 MAP" has more than a few sounds taken from the SC-88, most popular is the kic […]
Show full quote

They don't sound the same.
The SC-88 on the "SC-55 MAP" has more than a few sounds taken from the SC-88, most popular is the kick drum and ride cymbal in Duke3D track, but there are more.

Listen here for Duke3D Intro track.
http://www.wavetable.nl/category/comparisons/

Is the 8820 identical to the SC-88 in this case (because an 8820 is what was used in that clip)? That's quite a difference... I prefer the drums in the SC-55 clip on there versus the "SC-8820_55MAP" - the whole song sounds a little tighter overall on the SC-55.

I may have to look for BOTH a mkII for GM support and the slightly extra polyphony, AND a SC-88 for later MIDI that needs the extra voices.

mdfrankaudio wrote:

Is the 8820 identical to the SC-88 in this case (because an 8820 is what was used in that clip)? That's quite a difference...

Yes.
Also, some string instruments are different, so Warcraft 2 will not sound the same.
Moreover, some Envelope range differ form SC-55 and SC55-Map.

In short, if you want a SC-55 sound, buy a SC-55.
I suggest SC-55 MKII for everything MIDI related.

I remember comparing a Roland SC-88ST with the SC-55 map, and a CM-300 (home version of SC-55), and the main difference I could hear was better clarity from the SC-88ST. Tried various games and just ended up using the SC-88ST instead.