the xli (old xls series) has an advantage, it includes internally a switchable circuit that allows them to be driven by
consumer sources (dac/amps, pre-amps) the xti does not have this and it costs around 100 to 150 $ to add an
external one. Zeos used the xls to drive the 18" sub woofer he built recently. Power is the same but not
rated down to 2 ohms (this is a disadvantage). All comments here with regards to driving the phones.
The xti has a damping factor of 500 whereas the xli has only 200 still much better than the 50 for most audiophile amps.
The xti also has a fully adjustable DSP (8 band parametric and para-graphic equalizer with adjustable center
frequency, frequency band width range, Q factor and attenuation for each band and presets for Harman
Response curve for various speakers and phones, a limiter, a compressor, a delay and cross overs. All adjustable
by Harman software for the desktop connected via USB cable from amp to computer.
If you are on a budget and can get the dealer to offer you a 6 month warranty go for it, otherwise the
xti with all its DSP's and better than 500 damping factor works wonders.
to connect the phones to the speaker terminals you need to make one of these,
you will need a female TRS 5.25 connector and speaker cable and 4 banana plugs
put a piece of tape on the right channel side.