Hifimediy Sabre DAC was developed by DIY (do it yourself} enthusiasts in the purpose of making a really good but cheap dac that could compete against regular commercial DAC"s costing many times as much. It utilises a DAC chip from the ESS Technology which range of DAC chips is highly regarded amount audio enthusiast. You pay for the sound, not the enclosure. We use a small lightweight simple box, so you don"t have to pay extra for a bigger and more expensive enclosure. The power supply is very important for the sound quality. We use a high end ultra low noise regulator (LT1763). Features:- Output on 3.5mm headphone jack.- Volume Level is controlled by the normal volume control keys on your computer. (no need to use the volume control inside iTunes etc.)- No drivers required for Mac, Windows and Linux! - Normal line level output (2Vrms) when connected to amplifiers/preamps. For headphones the level decreases down to 1Vrms for 32ohm headphonesAdditional features:-Usb to optical converter. Outputs optical signal if you connect a 3.5mm optical cable in place of a 3.5mm audio cable. Can be useful for connecting your computer to another DAC without usb input.New batch uses USB receiver TE7022L:- Accepts 32khz, 44.1khz, 48khz, 96khz and 16/24bit input signals over USB. Most USB DAC"s use the cheaper PCM2704 usb receiver chips that can only accept up to 48KHZ/16BIT. Output levels:Open 2.2Vrms4.7Kohm 2.1Vrms1.8Kohm 1.9Vrms510ohm 1.5Vrms330ohm 1.3Vrms30ohm 1VrmsNormally amplifier inputs are from 10K to 100K ohm. Normal headphones are from 32 ohm to 250ohm.