Expensive Tube Amplifiers

Larry, I consider Mundorf and Hovland caps to be birds of a feather, in the sense they’re both modern high quality film caps. I certainly don’t think all modern caps sound the same, and it doesn’t surprise me that either one is preferred over the other by a specific listener.

My Dynaco/VTA amps have been modified a few times, but they still won’t sound like a modern CAT amp or other top end tube amp that has better iron, better caps, better circuitry, better power supply, better wire, better chassis, and better tubes....at some point everything matters, and the better amps leave fewer stones unturned. 

Once you’ve been exposed to a true SOTA amp on a complementary SOTA system you’ll likely change your mind about how most vintage good stuff stacks up.  There are definitely diminishing returns per dollar spent, but the performance forges ahead regardless.

Yes both are film, but the Mundorf has a particular sound that is quite different from the Hovland or other vintage coupling caps that one might consider such as chocolate drops.  However designed, I consider the Hovlands vintage, not modern, because they are long out of production and one cannot just order them from a parts supplier.  For speaker crossovers there are a number of old capacitors that sound really good in some speaker designs that are, technically speaking, defective (e.g., caps with very high measured DC leakage voltage, but they work fine in crossovers because DC leakage does not matter). I am not saying vintage parts are better than new, I am saying that the opposite is not universally true and that there are some really good old parts that are hard to beat in some applications.   

Vintage IS an imprecise term.  I am not disagreeing with the comment above that the Hovland MusiCap is the same type of capacitor as a Mundorf film cap, but the Hovland sounds much more like some quite old vintage caps that are vastly superior to the Mundorf in applications where that particular sound is sought.  This dealer/builder frequently uses such vintage capacitors and uses only vintage carbon composition resistors because of sonic consideration.  Some of his premium builds includes IRC resistors from the 1930's that are not easy to find.  Again, based on his customer's comments on the sound, modern parts may be substituted; like Audio Note coper or silver foil caps.    

My own amp is a relatively recent build, but, many of its parts date from 1940-1960.  The input and output transformers are probably from the early 1940's and some of the signal path resistors are quite old too.  Most of the capacitors are also very old paper-in-oil caps.  The modern parts are mostly in the power supply--new electrolytic caps, new power transformer, and new choke.  The parts choice was dictated by sound.