Can the HA75 damage my hearing?
Yes. Any time you are subjected to long periods of high sound pressure levels, you can damage your hearing. Always monitor your kids listening levels and consult local health and government safety regulations to ensure you stay within safe margins.
What is the benefit of tubes?
Tubes introduce warm-sounding even order harmonic distortion that is pleasing to the ears. This is why most audiophiles prefer the sound of tubes over solid state counterparts. The other benefit is the distortion acts like a natural limiter. This tends to reduce ear fatigue.
Do I need to warm the HA75 up before using it?
Yes. It takes about 15 minutes to achieve thermal stability. This of course produces a better sound as all of the components reach their optimum temperature.
Why is there no digital input on the HA75?
Today, there are many choices when it comes to DACs (digital to analog converters) and since most audiophiles have a preference, we felt that they would likely already have one that they like. The other issue is constantly changing standards. A good headphone amp with traditional analog inputs will never go out of style.
Can you explain negative feedback?
Negative feedback is used to control the amplifier from thermal runaway. This also results in less noise. However, may purists prefer to have as little negative feedback as possible in the signal chain to reduce phase cancellation. With the HA75, you can adjust to suit your personal taste.
Why did you incorporate a bass loudness switch?
Some will argue that true audiophiles may never use this function. However, when listening to music at low levels, bass energy can become too low. The loudness switch allows the user to add more bass to suit. This also allows users that enjoy listening to accentuated bass to share in the fun.
Why an external power supply?
External power supplies enable manufacturers to ship the same product around the globe without having to pay costly safety certificates. This makes the product more affordable for the end user. Further, power supplies tend to be the part of the circuit that is most subject to fail. This makes servicing easy. Finally, power supplies generate a ton of noise. This is particularly troublesome in small boxes. So removing the power supply lowers the noise floor.