• Audiophile 2496 - 2×2 analog + 2×2 S/PDIF and MIDI. Up to 96kHz/24 bit
• Audiophile 192 - 2×2 analog + 2×2 S/PDIF and MIDI. Up to 192kHz/24 bit
• Delta 44 - 4 in, 4 out with external connection box
• Delta 66 - 6 in, 6 out with external connection box. 4 analogue + S/PDIF
• Delta 1010 - 10 in, 10 out with external connection box. 8 analogue + S/PDIF + MIDI
• Delta 1010LT - 10 in, 10 out. 8 analogue (2 XLR with mic pre-amps) + S/PDIF + MIDI. May offer better audio quality than 1010(?)

The Delta PCI cards have been around since 2000 (?) and have long been well supported in Linux via the ice1712 driver, which should be included in most distributions. They handle various bit rates and depths up to 24 bit/96kHz. As of 2012 all these interfaces are still being manufactured.

Apart from the 1010LT the cards come with break-out boxes with 1/4“ jack sockets.

The optional Omni I/O box replaces the Delta 44 or 66 breakout box with one that has 2 microphone pre-amps with phantom power (these also accept 1/4” instrument jacks), 2 stereo auxiliary inputs, effects sends, 2 headphone outputs with independent volume controls and a master volume. The Omni is no longer available new, but some can be found on ebay.

Envy24control gives access to the internal mixers and is part of the ALSA tools. mudita24 is an 'improved' version. KEnvy24 is a KDE version.

• ALSA matrix
• Chipset information on unofficial ALSA wiki
• Delta 44 mods to reduce noise
• Using multiple cards - examples with 1010
• Sound on Sound review of Delta 66 from 2001. Also includes the optional Omni i/o front end with pre-amps and extra connections for effects loops etc. The Omni does not appear to be available any more.
• M-Audio support forum

• Forum user steevc has a Delta 66 and Omni i/o