Loopback

BurnInTest Pro 5.1
Fast, easy-to-use utility that simultaneously exercises all the major components of a PC, to test for endurance and reliability. Tests include CPU, RAM, disk, video, CD/DVD, printer, sound, serial ports, parallel ports, USB, tape, Network, video playback or customer developed plug-ins. Also, user configurable errors and logging detail, temperature monitoring interface, timed test runs, cyclic rebooting and EMC testing.
software, testing, troubleshooting, diagnostics, load, burn, pc, reliability, stability, serial,

ModemTest 1.3
ModemTest performs low level testing of dial up modems and telephone lines. Testing is preferably done with two modems but a single modem can also be used. Tests are independent of ISP and TCP/IP settings. ModemTest logs any data corruption and incorporates a modem speed test which reports the initial connection speed and the actual throughput. ModemTest helps to isolate faults with your ISP, dial up modem and telephone line.
modem, loop, back, loopback, connection, speed, bandwidth, internet, test, dialup,

PassMark SoundCheck 3.0
PassMark SoundCheck allows users to test their PC sound card, speakers and microphone. Verify that your sound card can record and playback sounds at various audio sample rates. Check the capability of your speakers to reproduce the highest and lowest frequencies (and your capability to hear these frequencies). Create perfectly formed test tones and loop them back into your sound card to look for distortion.
audio, testing, distortion, loopback, sound card, speakers, microphone,