UPDATE:
I tried the Empirical Audio Final Drive with the Aeris every way I could think of…. I am focusing on burning in the Aeris, so I did not unplug it and try the ODSE at this time (other then a quick test I will touch on, just to confirm a theory).
I reported previously on using the FD as a direction connection between ODSE and Amp (in series) - I preferred the pre-amp in my signal path with the ODSE. But I think that in other systems with "lesser" pre-amps it would probably sound better direct with the FD in series.
I make no specific commentary about the Aeris at this time as it is still burning in. I used it to compare locations of the FD only. I did NOT try running the Aeris direct to amp yet as it is not fully burned in. So you will have to wait for the Aeris direct to amps and Aeris - FD - Amps (direct in series) evaluations until next week.
Here were the configurations and commentary on each of the other configurations I tried:
Aeris - FD - Criterion Pre amp - Vertias Amp:
Definitely preferred running the DAC direct to the pre-amp. But my pre-amp HAS transformers in the inputs already and the Aeris is transformer coupled on the output, so this step was almost redundant. I believe most pre-amps don't utilize transformers (and I think most DAC's don't either), so this would probably be the best spot for a system with a transformerless input stage on the pre-amp and/or output stage on the DAC. Doubling up the transformers made the image a bit slurred and less defined, and muddied up the lower frequencies. I did not prefer it.
ODSE - FD - Pre amp - Amp (I only tried this briefly to see if using a DAC without a transformer coupled output would make a difference from what I found using the Aeris to Criterion):
Not the same effect as with the Aeris, which confirms what I suspected since I am almost positive the ODSE does not have a transformer coupled output stage. Again, I encourage Steve to chime in. I did not give this extensive listening as I will do this on Monday when the Aeris has a full 700 hours on it and I can unplug it and give the ODSE some play time. But I can say that the faults I heard between the Aeris and the Criterion were not there.
Aeris - Pre amp - FD - Amp:
My assumption with the Final Drive between the Pre-amp and Amp is that the DAC should have no bearing on the sound in this position. Meaning that the Final Drive should have the same effect on any music running through the pre-amp regardless of source, even if source was a turntable/phono-stage. So I used the Aeris in this test as source assuming that the FD would do the same thing to the ODSE. I will not run the ODSE in this configuration as I feel it would be redundant. You have NO idea how much time this is all taking!!!!
In this position it makes more sense as the Veritas amps do not have transformer coupled inputs, even though the Criterion uses transformer coupled outputs. I spoke with Merrill of Merril Audio and he chose not to utilize transformers on his input stage intentionally as he feels that transformers have benefits and liabilities and he did not like the liabilities, but he was actually VERY curious to hear the results of this test.
So…. Most of what I heard I liked very much. I can say that the Final Drives will be VERY equipment dependent! For my system, what i noticed is that adding the Final Drives to the system very subtly cleaned up the higher frequencies. I did not hear any additional extension in the highs, but they appears to be a tad crisper. The midrange was relatively unchanged. The lower frequencies clearly had a bit more extension and reach, but I felt that they were not quite as tight as without the FD in the equation; I would almost say the lows were more analog. Some would unquestionably prefer it, especially with a system highlighting accuracy as it would add extension and depth while creating a sense of realism to soften up an overly accurate bottom end. Edges were equally musical and refined with FD in and out and dynamics were excellent. Although I didn't think the FD added spark or punch to the dynamics, it neither retraced from them either. There were a few specific moments that I felt the music a little "slower" through the FD, although I can not explain it...
Besides the soundstage/imaging, all the other effects mentioned above were subtle, subtle, subtle. With the Final Drive in between the amp and pre-amp the stage/imaging was MUCH wider and deeper; like someone grabbed the stage and stretched it in every direction (left to right and front to back). I very much liked this. But with the wider stage, came a wider sense of spacial location. The best way I can describe it is using a video reference. The soundstage went from 4x3 to 16x9. But it wasn't like I was hearing a 16x9 source, it was like using the "stretch" function on the TV to stretch the 4x3 source to fit the wider screen. Everything was where it belonged, and accuracy of image placement was there, but each image within the soundstage stretched equally with the soundstage to fill the wider area. This gave my brain the impression of increasing soundstage and decreasing accuracy, which is not truly correct. In essence, it made it sound like I took my speakers and couch and moved them into a much larger room and just spread everything apart more.
I spoke with Merrill and he warned me that "more air is sometimes more smear."
I can't say for sure if thats the case here. But I can say that I preferred the wider and deeper soundstage with the FD in line, but I prefer the image "accuracy" with it out.
My impression is that, in a dedicated listening room, the FD would be a no brainer addition and anyone with a dedicated listening room needs to audition them. I think that my room's weaknesses and the specific gear I have accentuate what the FD does wrong imaging wise. And if it were not for the change in imaging accuracy (which I don't want to call loss in accuracy because it's not, its just a bigger image) I would unquestionably keep the FD in between the pre-amp and amp forever as I really liked everything else it does (except that slightly loser bottom end).
This is where it gets complicated…. I think that if I tried the MA1 with the FD and my pre-amp and amp, that it would give me more of what I want and less of what I don't. But I also think that I could use McIntosh pre-amp/FD/Mac amp with the Big6 and Revel Salon 2's and have a stunning performing system. The Final Drive clearly has special properties that, if well implemented, can truly improve a system. Trial and error will tell you.
In my system, ultimately I preferred it out. Primarily because of 2 factors; a slightly less controlled bottom end although it did extend to lower frequencies, and a change in imaging that was not to my liking. I will miss that massive soundstage though. I could literally get out of my chair and walk into it!
As I said, I did not try the FD in series direct between Aeris and Veritas amps as the Aeris is not fully burned in. I will try it next week.
I also did not give a full audition to the FD between the ODSE and the Pre-amp. I will do that next week as well.
I don't know if there is an acoustic difference between adding the FD transformer coupling on the input end or output end, but I guess I will see….
I welcome Steve, Guido, or anyone else with more technical know how then myself (which is probably all of you) to add to this. This is obviously not a DAC comparison, but it is interesting and the FD will be the perfect solution for some of you and clearly has the capacity to make huge changes in the system.
fin
