Adding a Nubus slot is useful, and I have one of these cards as it happens, but I am not sure how useful the DAV slot itself would actually be in a 660av, given the relative lack of vram (very important in the Quadra AVs), and given that the only cards that took advantage of the DAV slot in the 040 AV Macs were video cards. The 840av, with 2MB vram, was more realistically equipped for very modest video work, and of course both machines were good for audio out of the box, which has nothing to do with the DAV slot.
There were only ever a handful of Nubus cards that were manufactured to use the DAV-Nubus slot in combination, that combination being present in one of the 840av Nubus slots and in the 660av via this specific adapter as pictured. What these cards basically did was to pre-process video input so that the machine could then record 30 frames per second of NTSC or PAL input in near-broadcast quality in (as I recall) thousands of colours. The cards, in other words, took the heat off the built-in AT&T processor. Even an 840av so equipped, however, was never a substitute for the professional video studios of the day, though I suspect that they could have been used for professional audio work.
I have two of the Centris versions of the 660av (the same as the Quadra but for the badge), and have used them for different purposes in the past. Both are now idle, but one in particular used to get a fair bit of use. We moved from the UK to Canada fourteen years ago with two small children and a ton of VHS tapes in PAL format, which the new TV/ Video player could not handle. So I set up a convoluted system by which the kids could watch their videos, with the 660av doing PAL to NTSC conversion on the fly. This worked rather well, and it might interest you to know that the 660av was as good or better at this than the much more powerful 8600 that I later tried. Postman Pat was pleased.
I also had a 660av set up with a Geoport modem (the external one, on the dongle) as a telephony system at one stage. I only ran it for a few weeks, and for fun, but I do recall that it was very versatile -- you could call in and get your voicemail, forward messages automatically, set up multiple voicemail boxes and Applescripts to forward message reminders by email, etc. The quality of the audio both sent out and recorded over the phone line was astounding. It was like having your own reception system, which at the time was something shiny and new. The 660av was good for these kinds of little tricks.
I seem to recall that that worked best under 7.6.1 and one of the later iterations of the telephony software.
There were only ever a handful of Nubus cards that were manufactured to use the DAV-Nubus slot in combination, that combination being present in one of the 840av Nubus slots and in the 660av via this specific adapter as pictured. What these cards basically did was to pre-process video input so that the machine could then record 30 frames per second of NTSC or PAL input in near-broadcast quality in (as I recall) thousands of colours. The cards, in other words, took the heat off the built-in AT&T processor. Even an 840av so equipped, however, was never a substitute for the professional video studios of the day, though I suspect that they could have been used for professional audio work.
I have two of the Centris versions of the 660av (the same as the Quadra but for the badge), and have used them for different purposes in the past. Both are now idle, but one in particular used to get a fair bit of use. We moved from the UK to Canada fourteen years ago with two small children and a ton of VHS tapes in PAL format, which the new TV/ Video player could not handle. So I set up a convoluted system by which the kids could watch their videos, with the 660av doing PAL to NTSC conversion on the fly. This worked rather well, and it might interest you to know that the 660av was as good or better at this than the much more powerful 8600 that I later tried. Postman Pat was pleased.
I also had a 660av set up with a Geoport modem (the external one, on the dongle) as a telephony system at one stage. I only ran it for a few weeks, and for fun, but I do recall that it was very versatile -- you could call in and get your voicemail, forward messages automatically, set up multiple voicemail boxes and Applescripts to forward message reminders by email, etc. The quality of the audio both sent out and recorded over the phone line was astounding. It was like having your own reception system, which at the time was something shiny and new. The 660av was good for these kinds of little tricks.
I seem to recall that that worked best under 7.6.1 and one of the later iterations of the telephony software.