I'm the OP in this thread and you've all been supportive and helpful, so I thought I should report in.
To recap: The only "interface" I've ever used with my DAW is an ancient M-Audio Audiophile 2496 PCI card. It was the little brother to the Delta series, and it always worked for me, but it had limited I/O. Worse, it looked like there were not going to be any new drivers. I'm on Win 7. I don't even know if it will work on Windows 8, much less 10. So I went looking for a new interface.My biggest issue after audio quality was
latency: I typically record electric guitar through an amp sim in the DAW, which means I have to monitor at the very end of the complete round trip -- through the mixer input, into the PC, through Sonar and the amp sim and back out to the monitors. With the old PCI card. the latency in this round trip was negligible. But apparently PCI interfaces are going away. Would a USB2 interface be fast enough for me?
I didn't understand most of what you all told me here. I was looking for somebody to say "This box here, for this price, will do what you want." Instead I got theory and numbers, which I am not good at. I don't blame you for not answering my specific question
the way I wanted it answered. How could anybody else know what level of latency I could tolerate? In the end I figured I just had to work it out myself, face-to-face as it were, with a real interface. So I picked up the Focusrite Scarlett 6i6 (Note: I intend to use this with a laptop sometimes, so it had to be USB, not Firewire). I've only played with it for a couple of hours, and here's what I've found:
It works fine! According to the readout in the Sonar Driver Settings screen it's a lot slower than my M-Audio card, but it's not bad enough to throw off my playing. Also, I have loaded the most complicated of my current projects and experimented with playing the soft synths that are already part of those projects, and got similar results -- the latency is within acceptable limits for me.
For those who might still be interested, here are some numbers. Looking at them, it seems that the PCI card was quite a bit "better" than the Scarlett, and yet I am not having a problem with this amount of latency. There must be something I'm missing about latency, I guess:
M-Audio Audiophile 2496 PCI card, sample rate 96k, 24 bit, buffer size 256 samples ASIO reported latencies (includes buffer and hardware latencies)
Input: 3.1 msec. 299 samples
Output: 3.0 msec. 284 samples
Total Roundtrip: 6.1 msec. 583 samples
M-Audio Audiophile 2496 PCI card, sample rate 44.1k, 24 bit, buffer size 64 samples* ASIO reported latencies (includes buffer and hardware latencies)
Input: 2.4 msec. 107 samples
Output: 2.1 msec. 92 samples
Total Roundtrip: 4.5 msec. 199 samples
Focusrite Scarlett 6i6, sample rate 44.1k, 24 bit, buffer size 4.0 msec.** ASIO reported latencies (includes buffer and hardware latencies)
Input: 9.4 msec. 413 samples
Output: 13.4 msec. 590 samples
Total Roundtrip: 22.7 msec. 1003 samples
I always ran the M-Audio card at 96K, but before I installed the Scarlett I tested it at 44.1 because that seemed to be what most of you are doing. *For that particular test I lowered the buffer setting to 64 samples, although I didn't try to do any serious recording with these settings. I inserted an Addictive Drum track and noodled around on guitar, and there were no artifacts, so who knows? It might have been stable. Mainly I wanted to show everybody what the numbers looked like.
**On the Scarlett you can't set the buffer size in samples -- you have to use time. I started at 10 msec. and lowered it in steps until the latency was acceptable, which turned out to be 4.0 msec. I don't know how to translate that to samples, so I don't know how these settings compare.
General observations: My Schecter Blackjack with Seymore Duncan pickups breaks up the Scarlett's "Instrument" inputs, even with the pad. I have to use the "Line" setting in Mix Control. The knobs on this box are too small and too close to the edges of the fascia, thus too hard to see and use. I expect I'll get used to it, though, because -- and I hope I'm not imagining this --
everything sounds snappier through this box! I used to run the M-Audio card out through a mixer and then to the monitors. I boosted the bottom end a bit to compensate for my small nearfield speakers. Without this extra layer of electronics the sound is crisper and airier. I was never comfortable with the bass-boost kludge, but I felt I had to do something to keep myself from mixing everything with too much low end. My wife will be delighted to learn that I now need bigger speakers.
It's been a great learning experience, and it ain't over yet. Thanx everybody!