mrkniz wrote:To all who have replied to my query:
First, thank you.
I think my problem has been that digital outputs require balanced inputs into the amplifier, and my amplifiers only have RCA inputs.
Also, I checked out the MOTU 24Ao, and its outputs are either Phoenix connectors or DB25, and would require adaptor cables that would also only end in balanced connectors (or 1/4" STEREO--and I need 1/4" mono plugs, but they don't seem to exist). Bottom line is that I would have to buy a new amplifier with balanced inputs, and the Emotiva XPA-3 with seven channels costs $2000 (ouch!). Oh, that some company would produce a quality interface with twenty-four (or more) 1/4" outputs with Thunderbolt and AVB connectors, and nothing else!
Although there are ways to convert the balanced outputs of a professional or semi-professional audio module to unbalanced, you lose the balanced line noise reduction capability when you do. But it can be done. It is especially easy to wire the 24Ao Phoenix connector to a wire with an RCA plug on the end. Also 1/4" tip-ring (TR) plugs can usually be inserted into tip-ring-sleeve (TRS) jacks with no problems but again you lose the noise reduction of the balanced circuit. The proper way is to go through a Balun (balanced-unbalanced) transformer which is TRS (Gnd, -, +) in and TR (Gnd, + out).
The real conflict here is the collision between the professional audio world and the consumer audio world. The pro audio world uses different connectors, different configurations and different reference levels from the consumer electronics world. Your amp is from the home theater consumer world and the MOTU and the ADAT are from the professional world. But it is possible to purchase the cables you need to get them to work together. CablestoGo.com
I like what Iain had to say about shying away from ADAT--it's just not a technology with which I'm comfortable. So, for the time being I'm putting any further purchases on hold. Eventually I might buy a second 16A or an 8a. Right now I'm building new housing for the speakers, then a new console, and then doing some more upgrading of the electronics.
ADAT is a very old format created for an early 8 channel, 48kHz digital audio tape on a VHS video cartridge. I do not think there are many ADAT machines left but the digital audio format lives on.
As an aside, this has been my first post in quite a long time, but I do read the forum every day with my morning coffee. What a great group of people!
Thanks again, Ken