NVA, which used to stand for Nene Valley Audio, is a British company that has been in business for over 30 years, happily making amplifiers that do not conform to the usual trends. Mr. Richard Dunn, the founder of NVA, used to design pro amps for rock bands and so forth back in the 1970's with his company then being known as Tresham Audio. However, he never thought that pro amplifiers were hi-fi amplifiers so far as sound was concerned, and when the opportunity arose to start NVA he indulged himself in going for sound rather than ruggedness in his amplifier designs.
One of the things that beset him at first was that his cased prototype amplifiers never sounded as good as the experimental breadboard setups, which led him to investigate case design. Remember, we are talking years before the high-end community worried about such things. So, he discovered that steel was no good as a case material, and that even aluminium produced circulating eddy currents (that's how a utility electric meter's little disc turns around, by the way). Even screws holding circuit boards to the chassis caused problems as well. The eventual solution was to use plexiglass / acrylic. Acrylic prevents electrical continuity, so the case behaves as no case. Instead of screws to hold everything together structural adhesives are used.
Then there was wire, and the associated dielectric effects from the covering that is usually applied. Obviously, Teflon is nice, but it is expensive. Even better is nothing at all, and so Mr. Dunn embarked on this approach, ending up with a large gauge tinned copper wire used to carry all the power supply currents, output currents, and a really rugged grounding system. As a compromise, the inputs are wired with silver-coated stranded copper wire with a PTFE (Teflon) coating.
The result, when one peers into an NVA amplifier, is like nothing you've seen before. Large hunks of tinned copper wire float at various heights around the amplifier, making it truly unique. Thankfully, electrons do not suffer from OCD!
The circuit boards don't look like the latest all-dressed computer types with green coating and carefully marked component locations. They are free of that stuff and the dielectric effects they cause. The circuit tracks on the boards are hand-designed with no sharp curves anywhere. The layout may look untidy, but each piece is where it is, because that's where it sounded best. And you will note that the bypass capacitors used are very expensive Wima 0.1 micro-farad polystyrene types, generally acknowledged as being second best only to Teflon.
Then there was the problem of volume controls (potentiometers). Stepped Attenuators are best and you can go mad with high quality expensive resistor choices, lower expense but still with quality requires Log A plastic film potentiometers. Both are available with NVA passive pre-amps.
What about output inductors following the output transistors? They're usually included to "pre-load" the amplifier to deal with capacitive speaker cable. No good. Out they went. Now you have to be careful with the speaker wire you choose, because low capacitance is a prerequisite, and bi-wiring which would double capacitance, is out as well.
Naturally, Mr. Dunn then developed some speaker wire with incredibly low capacitance, called LS series. It really shows how an NVA amplifier should sound, and adding it to your present system will wake it up as well. Inside each braided sleeve are many different silver-alloy teflon-covered solid-core wires, quaintity and spec depending on model and there are separate cables for positive and negative, meaning 4 cables for a stereo system. It's by no means the most expensive cable out there, and you don't have to buy it twice to bi-wire!, as the insulated cores can be separated.
So what we have is a truly unique amplifier which requires some owner involvement, and quality sound that you simply cannot purchase for less. One of the biggest surprises for an NVA customer will be to find out how "quiet" their amplifier is. Virtually zero hiss and hum with no signal, even with your ears pressed up to the speaker.