I purchased the EXTC-SA a few months ago and so far it has more than proven its worth.
The EXTC-SA is delightfully intuitive. Unbalanced and balanced inputs and outputs are clearly indicated on the back. The send and receive knobs, the polarity reverse button and blend knob work just as one would expect. The A and B loops are a great feature and I find them useful for for auditioning different signal paths or to run in tandem to achieve even "fresher" sounds! The unit in general feels solid. The buttons and knobs operate smoothly with even sensitive adjustments making an audible difference--a sure sign of a quality piece of kit. I like that it can be rack-mounted, taking up only 2U of space. All of this means, to me at least, better integration into a studio environment and fewer interruptions to the creative flow.
This thing excels at its main purpose of being a high-quality effects loop. I haven't noticed any signal degradation or noise, any latency, just hi-fidelity goodness. If it "colors" the signal, it sounds pleasant to my ears. I've used the EXTC-SA on drums, vocals, synth, DI guitar and bass and they all sound fantastic. For instance, I added some nice saturation to the kick and snare by running them through an overdrive pedal. It completely changed the attitude of the song for the better in my view and has inspired me to take a new approach to mixing and future recordings. My band really digs how the final mix turned out. Another example is when I ran the kick through the EHX Bass Mono Synth pedal. The kick essentially became the bass line and I wrote a song around it. The doors this thing can help to unlock are endless!
The EXTC-SA also performs wonderfully as a reamp box. The tried and trued method of reamping DI bass/guitar tracks through a miced up amplifier, such as the Ampeg PF50t or Fender Deluxe III in my case, works brilliantly. Blend the DI with the reamped signal captured via microphone, adjust phase accordingly and boom, ready to rock and roll. That's just one of many applications, I love the attitude of vocals through the Fender amp. A snare track or drum bus through the actual spring reverb of a Fender tube amplifier is a thing to behold. I recently reamped a snare through a PA speaker set up in a long, concrete hallway and used a condenser mic to capture it. It turned the song into this huge, menacing monster that enhances the already dark mood of the track.
In addition to the aforementioned points, I've found that the EXTC-SA saves a bit of processing power. Some plugins can really drain your computer and this helps to keep the dreaded "overload protection" or equivalent failsafe at bay. In a pinch, it could be used as a DI. And live, if the mixing desk has no effects or the engineer has a chip on his or her shoulder and refuses to give you reverb or delay, the EXTC-SA can save the day!
The EXTC-SA is one of the best musical investments I've made. The practicality and avenues of creativity it can take you down make it completely worth the price tag. Yes, one could use plugins to achieve similar results and I still do! However, I find the tactile element of hardware, pedals and amplifiers in this case, lends something really special to the creative process. I know a lot of this stuff can be subjective, all I can say is that I dig the EXTC-SA and I think some of you might too! Happy recording!