Summary: I bought the MDR-DS6500 and connected it to a flat panel TV via the supplied (ultra thin) optical cable. With the base unit's special effects and compression switches both set to off, the headphones, which I found to be lightweight and comfortable, consistently produced clear untroubled sound with no variations in volume, even when I walked from room to room throughout the house. My only complaint is the volume control, which I found to be hard to feel and adjust.
Summary: The Sennheiser's and the Sony's both sound great they have a lot of punch and crispness. Sennheiser specializes in headphones and microphones (I understand), so the RS 170's have the signature sound of the excellent Sennheiser products. They do not disappoint in terms of audio listening quality but then neither do the Sony's. The amp in the Senheiser's seems a bit more powerful (picks up signals faster) than the comparably priced Sony's.
Pros: great sound with excellent frequency response, with both analogue and digital input
Cons: sony does not allow you to buy stand alone headphone to use with the base station
Summary: So, I've long been wanting a good wireless headset that could connect to both my computer and office Blu-ray setup (40-inch Google TV in this case) at the same time. So far, this is the best set I've seen on the market, and while it's close to perfect it has a couple of minor issues that prevent me from giving it five stars.
Summary: I think by 7.1 it means using the virtual sound technology to upmix either 2.0 stereo sound input or 5.1 channel sound input to 7.1. I don't think SPDIF supports 7.1 sound. I have ordered it and we'll see soon. Let me put five star for now.
Summary: To previous reviewer (Patatas): The Optical input will pass the older compressed DD-EX and DTS-ES 7.1 audio formats. It will not pass the new uncompressed Dolby TrueHD and DTS-HD Codec, HDMI is required for this. When using the optical connection, a Dolby TrueHD or DTS-HD source will be down-converted to regular DD or DTS.