Dvdgreco,
First here is a review you may have seen on the product you have an interest in:
http://www.enjoythemusic.com/magazine/equipment/1200/herronaudio.htm
Next, I have been interested in his equipment before and came close to purchasing one of his preamplifiers.
He is a trained engineer and has labored over the years to develop his equipment. The piece you are looking at or own is older generation, which could mean it is time to send it back to Keith Herron for a check out. The only thing would be a capacitor replacement. My conversation with him reveals him to be an honest gentleman. He is not a rip off artist. His equipment is real and he, like all designers makes his own choices. Although, I have not heard his equipment personally, it appears well built and specified.
One thing that is very important to me and very elusive to find is a quality Volume control, and I believe that is what drew me to his preamplifiers at the time I was interested.
Again, it appears he has taken great care to provide a Volume control with sufficient span to accomodate mating with different amplifiers.
The unit you are discussing indicates 14 dB of gain and an output impedance of only 100 ohms with 128 stepped attenuator. I would ask Keith if I were you, by calling, but I can only assume that these steps are lets be conservative and say 0.5 dB increments and not some sort of tapered stepping.
This means you have 64 dB of Volume flexibility and with 14 dB of gain, you have -50dB attenuation at your disposal. I can say that if you confirm what I am exptrapolating above as true, then I recommend the compatibility part of this unit for almost any amplifier with standard impedances (input) of 10 k ohms or greater. I think the rule of thumb is lower than that...maybe...but, that means you should expect no low frequency roll off and full transfer of the signal to your amplifier.
Now, that said, he does use FETs on the input of this preamp. Purists would take issue with that. The review is positive and if you have the opportunity...let your ears be the guide.
Make sure you invest in serious power conditioning with time as your budget affords. I personally endorse the Furman IT Ref class conditioners and the SPRi 20 Voltage Regulator to not only preserve your tubes, but to get the very most from your sound system.
These upper end Furman products are well built and categorically will make a sonic difference.
There is a series one step under the Furman Ref class...like the Elite 20PFi that may be an economical compromise to save money and get you to where you want to go.
I have not heard the Elite series in a system, but they specify in a way that indicates similar circuitry to the Reference series for the functionality they do offer... The Ref series has massive Torroidal Isolation Transformers.
I do not recommend this for a number of reasons, but if you want to experiment (and save money)...you could add one more box to the Elite Series (if you actually embrace that road)...something like a very large Tripplite (or some other competing well reviewed brand) Isolation Transformer... I cannot tell you whether this will work well, other than in theory it should...and, I can also say...as much of a kluge as this proposal is...I actually think it could work well...this is for you to chew on.
Ultimately, I would steer you to their better units and be done with it.
okay, you ask about the "Mccormack DNA-1" My quick research indicates this is an amp from the 90's.
First, I have indeed heard McCormick amps. They are very respectable and a sold step up from say Rotel RB-1090 (the only Rotel amp that has any merit...but, is only suitable for very specific applications). However,the AMR equipment eclipses them. Since, you are building a system, this amplifier will be your weakest link and get in the way of you realizing the potential of the AMR equipment.
The Herron Equipment is probably good enough to transfer a lot of the goodness of AMR equipment. The McCormick, as respectable as it is...is not in the same league remotely. In addition, you will likely need to re-cap the amplifier due to its age. I would steer you away from it, unless you already own the McCormick. Yes, they do not cost that much used...but, there is no free lunch. Do NOT buy one.
YES, both of these units are not up to the refinement of the AMR equipment. However, the Herron may be more in the bottom running. The McCormick is out. The only think I can think of is a completely new set of insides for the McCormack, essentially turning it into the amp you should buy in the first place...and by the time you do that...if you are fixated on purchasing the AMR...you need to get an appropriate amplifier in the same league as the AMR or plan/budget for getting the appropriate amplifier in time that can give you all of the AMR goodness.
Your system concept is currently not in balance. It takes one to know. So, nothing wrong there...you just need to bring you system idea into better alignment.
I encourage you to research more to determine some better matches. At this time I will refrain from making any recommendations, because this will turn into a novel. Good luck!!! And, Cheers!!!
-----
To: Essentialaudio, You have disclosed you deal AMR. Thank you for that honesty and please continue to do that, should you choose to post further.
However, IMHO
One last note: The AMR dealer on here. It is good you disclose you are a dealer, but I think you should not be posting to hobbiest forums, when your agenda is to push your equipment, no matter how much I hold AMR equipment in high regard. I just think you need to market another way. It is intrusive. I submit that to your respectfully and ask you to refrain and get customers by working through your own web site rather than push your equipment here. Please, let customers come to you. This is meant to be constructive. Thank you.
We want people to post that do not have an agenda. That way hobbiests can actually just learn from each other in an unbiased manner. Believe me, we will come to you if we have further questions we think you would know the answer to. That said, you are correct mostly in saying that one must listen to the DP-777 and the AMR-77.1 and see for themselves....but, to really do that properly they would need to get units from you on loan and put them in their own system.
Now, for potential customers near Essential Audio, it is unscrupulous to borrow any of his equipment if you do not sincerely plan to spend your money with him. He is a busnessman and if you plan to buy used, please do not waste any dealers' time. I do not ever go into a dealership or ask more than a token question...and usually none, if I plan to buy used. I consider that inappropriate. Yes, I did do this in the beginning of getting into this hobby. I do not do this anymore. It is NOT a good thing to do. Thanks for everyones consideration on my many remarks.