The Acurus is certainly up to driving your Thiel's, but, other than what it can do in the lower registers, I don't think you'll care for it with the Thiels. There is a conrad-johnson MF 2300 currently up for sale here on audiogon with an asking price of $1000. I don't know the seller or anything about his particular amp, but, I think you could be very happpy indeed with this combination and stay close to your budget. Good luck!
To let you know where I'm coming from, a few years ago I owned a pair of Thiel CS-1.5s that were driven by Rotel RB-981 and Acurus A-200 at various times. I also used a pair of RB-981s bridged to mono. My impression was the Acurus may be the most uncolored/accurate amp I've owned. This could come across as sterile but plenty powerful. The Rotels were much warmer sounding, and that was a good thing with the Thiels as I found them to be analytical to the max. As Ive never heard the 1.6s, this should be taken for what it's worth but I preferred the Rotel amps with the 1.5s. I also owned an A-250 but not with the Thiels. The $499 price seems a bit high for the A-250 or else I sold mine way too cheap.
Long ago I tried an Acurus 250 with a pair of Thiele 2_0's. Pretty much unlistenable as the speaker revealed the acurus as being very harsh and "unmusical"...
I replaced the Acurus with a McCormack DNA 1. Much, much better. Of course the price (used is closer to $900 than the $499 for the Acurus.
On the other hand you do buy into great product with a proven upgrade path (SMC).
Just for yucks I looked as to what DNA"s were currently on the market. Found an $850 DNA from Tyler !!! Wow - ya couldn't have much better karma than that - an amp designed by an industry legend (who happen to be a great guy) from a great speaker designer who also happens to be a great guy.
So, how did the Benchmark compare to the RSX-1067? If it was an improvement, then seek out a 2-ch pre-amp with HT bypass. That way you can keep your current setup and use the new pre-amp for just 2-channel listening. This is the best way to optimize your system for 2-channel. HT pre/pros (and receiveers) aren't great performers for 2-channel unless you get into some very high end components. I think CJ, Rouge, Sonic Frontiers and others have the HT bypass feature.
Hardly a "gimmick". Relieving a driver from this stress, reduces compression, allows for greater dynamic range and if the subs are seperately powered, allows the main amplifier to work with less stress. This may be more so with typical class A/AB amps which may be able to maintain the preferred class A bias longer. All in all it may change the true sound and performance in a good way. Thiel offers both active (more expensive), which is what would allow for the above, and passive filters(less expensive), which would not offer all of the above mentioned advantages. Balancing all this can be tricky, but, Thiel seems to have found a unique way to make it easier than is usually the case. This may all be academic, as I don't think your budget contraints will allow for this option.
Okay, just for fun I set the Pre/Pro to Stereo (from bypass) and told it the main speakers were small/60 and then small/80.
The effect was less than wonderful. The Thiels lost detail and the soundstage crumbled. I did pick up a hefty amount of bloated bass from my REL subs. Didn't hear enough to get me on my hands and knees to dial them in. I'm sure the pre/pro didn't help either.
I'll keep an eye out for a tube pre with HT bypass....it seems like a logical next step.
I hear the logic behind the low freq shuffle, but can't let go of the simple fact that a speaker is engineered to achieve a certain level/type of sound across a known range of freq.
If we change that range - wouldn't we ideally want to change the speaker design to take advantage? When the low freq are no longer present, how can a vent or port function as it was meant to?
It's probably painfully obvious that I'm a writer by trade -- and not an engineer.
Oh, and I can afford the Thiel Bypass Box -- but the Subs are another story.
I've only heard the monster one at the local dealer and that was with 7.2s -- so I don't know what I was actually hearing.
The best you can do is use your thiels with the subs for stereo (what is home theater anyway?) Yes you need to drop the lowest freq. from your amps and speakers, the mids and highs will be unbelievable. You dont have to change the design of the speakers; Imagine you have a sports car going uphill, without the lower frequencies your sports car will go only downhill, much faster and easier and you dont have to change the engine of the car!!! Connect the Benchmark directly to a "y" connector, from there one RCA cable to the subwoofers and the other to a passive line level Cross over (or any line level XO) into the amps. Going down to 50 hz instead of 20hz will be a huge benefit for the amps, and the speakers will be happy also. I wouldnt try to go all the way up to 80 hz, it is more difficult to match the subwoofers the higher you go. Remember the quality of the line level cross over is "very" important for a good sound!!! Do this and you will laugh when you hear other much more expensive systems!!!! yours will be excellent!
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html This is what I am talking about...dirt cheap also!!