I’ve got Model 5’s too and am very happy with them. The advice you have gotten to contact Vandersteen is good, that would be a good second step. First step is to read the manual thouroughly and get yourself very familiar with how Vandersteen wants you to set up the speakers. That will save some embaressing pauses while you are talking to them! If you don’t have a manual they have one for the 5A on the website, it’s essentially the same as the manual for the 5.
I did look up the McCormack DNA 225 and the input impedance (from a Stereophile article) is 100K Ohms. The manual tells you how to set the dip switches in the high pass filters. With respect to using balanced filters with a single ended preamp, the manual doesn’t address this, but I think a single ended filter would be best (mine are balanced so I can’t help on the “trade”). An alternative would be to get a balanced preamp. A balanced preamp has advantages from a noise perspective and there’s a good opportunity for a significant increase in performance! Not sure if there is a McCormack preamp with balanced outputs, but there are plenty of used options at reasonable prices.
One bit of advice on the filters (and the crossovers in the speakers) is they are battery biased. Similar to AudioQuest cables they use a battery to bias the capacitors in the filters. This is a contentious topic for some folks, no need to go on about it here ... Vandersteen uses standard 9 volt batteries which are soldered in place. The batteries they use (Duracell alkaline) are replaced every seven years. Yours could be well past that. Vandersteen marks the date when they do it, if an owner did it themselves hope they marked it too. I will say soldering a wire to a battery terminal is not an easy task. Too much heat will ruin the battery, but you won’t realize it unless you check for 9 volts after you finish the job. I know this from experience! Vandersteen charges $96 for the filters and $189 for the speaker crossovers (three batteries) so keep that in mind.
The spikes use a 1/4-20 thread and are 1-1/2” tall which is optimized for the speakers. Similar to the 2Ce the speakers need to be tilted for optimum tweeter “aiming”. At $22 per spike the cost will be $132, but that’s not much more than a generic spike. You also need fender washers for the rear spike to adjust tilt. A low cost temporary alternative would be a furniture glide. They are a threaded shaft with a round, flat base (instead of a hexagonal head). They can be quite useful when positioning the speakers in your room since moving the speakers is MUCH easier than with spikes. Be careful when putting whatever feet you choose, the speakers weigh a lot and can tip easily. I came very close to dumping mine when changing feet by myself. A second person is highly recommended!
The next big hurdle will be setting the low frequency level controls. There are 11 frequencies that can be a adjusted a slight amount to optimize the low frequencies. Adjusting the controls can take a while and requires at a minimum an analog Radio Shack sound level meter and the Vandertones frequencies found on the Vandersteen website. The manual goes into some detail how to do this, but Richard does say, if you can’t get it right just set the controls at the neutral position.
That’s what I can tell you right now, if you have more questions I will try to check this thread regularly and respond.
