REL Subwoofers: Version 3 vs. Version 2

Does anyone know what the differences are between the mk2 and mk3 REL subwoofer series are? I have the opportunity to buy a used Stentor 2, and would like to know how it differs from the 3 series. Also, is the Stentor too big for a medium sized room (16x20)? Sumiko suggested that it might be, and that I might be better off with a stadium 3 or storm 3. Advise appreciated! Thanks.
I had the same question when I was trying to decided which sub to get. Here is the conclusion that I came up with. If you plan to use your sub for music and for the LFE in home theater, the difference will be huge. If you are just going to be using it for music, the difference will not be as great. I believe all the version III's comes with the ability to switch between using REL's internal crossover for use in 2-channel audio and bypass for the LFE for movie soundtracks by a switch on the sub. With the previous version, you will have to physically disconnect the RCA's low level input when using the sub for music or disconnect the high level input for movies soundtracks. If one does not do this and both inputs are hooked up at the same time, your bass output will sound like its doubled. The version III's also come with a bit more power with an improved enclosure.

I don't really believe you can have too much subwoofer as you can control always control the output. I am using a Stadium III in a room that is 15x17x7 and am very happy with the performance. I think a lot depends on your main speakers. I am running the REL with Thiel 22's and crossing it over at 23hz, the second to lowest crossover point. I would personally prefer a Stadium III over a Stentor II.

Hope this helps you in your decision.
I mostly agree with Island, except for the part about the bass being doubled. I've been researching the exact same thing recently.

If you have both inputs connected there are two issues:
1) Crossover freq. With the II, each input has the same crossover point as you dial it in. This could be a problem depending on your main speaker and where you set the xover. For HT, the THX specs call for 80hz as the correct xover for the .1 channel. If you have full range speakers this is likely too high and you will have to manually adjust for each mode. For either the II or III keeping them both connected should not matter that much because in two channel mode your pre/pro should shut down the .1 output so no issue. In HT mode, the low level input will reproduce the .1 channel and the high level inputs will reinforce the left/right mains subject to the xover concerns earlier. The III allows you to bypass completely the xover for the low level input making it ideal for a 2-ch / HT combination.

2) Is level matching. With the II there is only one level control. You can set it for 2-ch with the high-level inputs and you should be able to match the .1 level with the pre/pro .1 output control. The III has separate level controls for each input.

My pick is a Stentor III
btw. Eric at REL tech support is great to communicate with. He responds in less than 24 hrs to your questions.
Personally, I'd be looking at 2 Strata IIIs.