Delay... not the good kind

While wandering home and thinking about what to add to my blog I noticed a board in the tube station covered with "minor delays" signs and so I will talk about delay, well actually latency but meh.

When doing digital recording it is always important to consider latency or the time delay between a signal entering your audio interface and it leaving through your monitors. The more complex your studio and the more software effects you apply the larger this effect becomes. And it can be very annoying! You can be happily rocking along to a click track only to play it back and find the timing is out by a few tens of milliseconds. Having said that most modern audio interfaces are excellent at compensating for this and are often advertised as "zero latency". The particular problem I have is that I have two audio interfaces (see My Studio below) - an M-AUDIO Firewire 410 and a Line 6 TonePort UX2. I like to have my monitors connected to the 410 but record most of my guitar stuff through the UX2. The two methods I use are as follows (neither ideal but nothing is in a home studio):

1. Have input and output set to different audio interfaces in my sequencing software. Goodness: easy to record and route signals. Badness: Latency, lots of. Most software generally seems to prefer dealing with as few hardware devices as possible hence the problem. The latency is correctable (well in Ableton Live it is) but also variable.

2. Use my 410 for the audio input and output and feed the digital output (s/pdif) on the UX2 into the 410. Goodness: Minimal latency. Badness: Not as flexible as the first idea and also can be temperamental as you have to sync the clocks on the two interfaces. Basically my 410 has to use the clock source in the UX2 that is transmitted with the digital audio by the s/pdif cable. If this clock signal loses sync (as seems to happen whenever I turn my cooker on!) all my music suddenly becomes horribly distorted. 

Actually the other option is to keep swapping between interfaces but this requires a lot of cable changing each time I want to play something back and I can't then always monitor using the 410. Anyways I am starting to prefer the second option especially as the reliability of the s/pdif connection seems to have improved now I have the most up-to-date software and a faster computer, or maybe I'm just imagining stuff. It does however bring me to the topic of clock sources in digital recording but I want food so I'll leave it to another day.