Solution: An M-Audio-recommended PCI Firewire card solved this problem for me. The VIA chipset firewire on my Asus board was the cause of all the noise. ---------------- Original post ---------------- Wondered if anyone here can help me, I've been struggling to figure this out all day. When I try to record, I get nasty crackling along with the audio signal. I uploaded a brief example if that will help identify the problem - sorry it's quiet, I was trying to make the point that nothing's clipping! Octopre The crackling is louder when the input signal is louder, it tails off with note decay and there is no noise if the input is silent. It's almost as if the input signal is like a "carrier" for some interference from somewhere. I also tried monitoring through my card's direct out and there's no crackle there, it only shows up on a recorded track. I'm also not asking much of my computer - just one track recording at 44,100, no tracks playing back. I'm pretty sure it's an issue with my PC rather than my audio interface (M-Audio firewire 1814) because I tried recording through my mobo's onboard line input and got the same crackling. Things I've tried so far: Disabling mobo's onboard audio and LAN. Physically unplugging all peripherals except audio interface, mouse, keyboard and monitor. Checking/changing PCI latency (seems my audio interface is the only device using the PCI bus anyway). Different cables. Different instruments (a Warwick bass, a Stingray). Different recording software (PT M-Powered / Audacity / Windows Sound Recorder!). Checking/changing sample rates/bit rates, and buffer sizes (up to 4096 samples and still no change). Latest drivers/firmware for the M-Audio interface. The only thing left to try that I've found on my Google travels is a different Firewire chipset (mine's VIA, M-Audio recommend Texas Instruments) but given that I get this crackling from the onboard audio on my motherboard too I don't think that will help. PC consists of: Intel Core 2 Duo E6600 Asus P5B-E motherboard - Intel P965 chipset - VIA OHCI Compliant IEEE 1394 Controller - Attansic L1 Ethernet Adapter nVidia 8800GTS graphics (PCI-E) Western Digital 250Gb SATA drives (x2) Lite-On SATA DVD-RW (x2) It's all in an insulated Antec P182 case, with a posh-looking Corsair 620W modular PSU, I deliberately bought very quiet high-capacity fans. Any suggestions? This is the first time I've tried to record on this PC, and I don't have another firewire-equipped PC available to try this box through.