Thanks for the ionfo. That makes a lot more sense to me now. I'll do some more research on my end. I did contact the manufacturer quite a ways back, but I've lost the e-mail. I'm sure there is a compatable card, I just wanted to avoid having to buy it if possible. Thanks again for the info above. Very well explained, Hoco.

Guys, re the sound card compatbility, there are a few versions of the PCI standard, each operate at different voltages (5v and 3.3v) so your Mac will need the correct card. For advice on this I suggest you must check out www.motu.com/techsupport...ompatibility

I'm in the same boat - I have a pre Intel G5 Power PC so I think I need the PCI-X version (i.e. lower voltage card, but not with the foobarred PCI-e pins).

Regarding 24bit vs 64 bit etc... all pro audio gear these days takes a word length of 24 bits, except older stuff like DAT machines whose converters were made to reflect the 16 bit CD standard. So CD audio is 44k 16 bit, DVD is 48k 24 bit, HDVD is 24bit 96k/192k etc. Sample rate goes up, but the bit depth is regarded as sufficient for all purposes - because converter circuitry doesn't yet have the ability to capture bigger dynamic ranges.

The reason you see higher internal bit depths is that when processing the incoming 24 bit stuff, plug-ins and digital mixers need a lot more extra bits to accurately do the floating point math needed to fade, filter and flange the raw audio. Its like 5/7 = 0.7142851429. If my internal resolution was just 24 bit then after calculation 1 I would have 5/7 = 0 (or maybe 1 if I randomly 'dither' it up) in my result box... that's not going to sound great, as any subsequent calculations are going to miss those extra bits a lot -

So, they use lots of bits internally and then truncate the extra bits before the output. They might also apply dither to the 24th bit, to hide the sonic side effects of chopping off the lower bits.

Pro-tools mix busses use 56-64 bits, MOTU mastering plugins use 64 bit (even though internally DP5's mixer is only 32 bit), a Ramsa digital desk is 32 bit DSP, a Boss ME-5 will be 16 bit if you're lucky...

Check out this old article remixmag.com/mag/remix_f...w_computing/ -
""The best converters today can't even fill a 24-bit sample with complete accuracy, so the extra bits that a 64-bit double-precision float could provide wouldn't be able to help.” However, for devices such as digital mixers and outboard effects gear, he adds that a 64-bit floating-point signal could be very useful, as it would allow you to master using outboard gear while retaining the full internal precision at each processing step."