McCormack SMC Audio upgrades: how good are they?

Just a couple of additional comments if I may... A previous post alluded to the need for a solid-state preamp if you went with the further Platinum upgrade, and this is not strictly accurate. Your current DNA-125 Gold has a high input impedance (100KOhms) which makes it suitable for use with any type of preamp. The Platinum upgrade normally includes the addition of balanced inputs, and the method I use for this reduces the input impedance to 10KOhms (also true for the monoblock versions). This means that whatever preamp you choose should have an output (source) impedance of 1000 Ohms or less, and this leaves out a few tube and resistor-based passive designs. Most preamps can drive a 10K load with no problem, but you do have to pay attention to impedance matching when making a choice.

On the other hand, all of our work is effectively custom, and you are not required to add the balanced-input option if you don't want it. For your DNA-125, the real step-up is to the Plitron power transformer which more than doubles the amp's current capability. Then there are a variety of capacitor, resistor, and wire upgrades that lift performance considerably further.

Food for thought...

Steve McCormack
SMc Audio

Steve,
on a side issue, how would you characterize the improvement in sound due to the input transformer in the case of the DNA125/0.5/etc. (other things being equal)?
thanks
Luigi

Hi Luigi -

I now use Lundahl amorphous-core transformers in my amp upgrades (and in my VRE-1 preamp). I started with Jensen transformers, but switched a few years ago when I found the Lundahls offered better transparency. I originally used input transformers to provide a balanced option, but I then found that I preferred the sound of my amps with them, regardless of which input (balanced or unbalanced) I was using. First of all they provide complete immunity from DC and RFI, and well-designed units have outstanding common-mode noise rejection (CMRR). This allowed me to simplify my amp's input stage, and the net result was sound that I hear as cleaner, clearer, smoother, and more "pure" if you will excuse the expression. And keep in mind that my design handles both balanced and unbalanced signals via the same path (the only difference being the input jacks) so you get the benefit of the transformer either way. Of course this only works well with great transformers, but that is the only kind I use ;-)

In short, I feel the input transformers are a sonic benefit even if you use only the unbalanced inputs. The only downside is the relatively low 10KOhm input impedance, but this is an issue with only a small number of preamps.

Best regards,

Steve McCormack
SMc Audio

I had my DNA-1 Deluxe upgraded to the gold edition by SMC Audio. I love the sound stage improvement and the low level detail that is unmistakably there. There is less listener fatigue or "veils" lifted between the speakers and myself. I can tell as I've had this amp for many yrs. I have one issue with the upgrade which I emailed Steve's sales group and called the primary person in sales complaining about. When I turn the amp on there is a significant "POP" as they have removed the timed relay we are used to that lets the amp startup surge happen before the speakers see any current. I was told this was done to improve the sound which I countered with "Why wasn't I told this before purchase" - they forgot. Is there anyone else dealing with this?

Do you have the option of leaving the amp on continuously?