Thanks for the reply, Andy. I really appreciate how hands on you are here with everyone's different comments here.
If you could give me/us some advice, what's the best way to run the HA-300 if you're using it with a preamp and if all of the volume control will be done upstream via the preamp or if someone digitally reduces the volume in their system before the DAC?
Is it just simply turn the volume all the way up and then the pot is "bypassed"? I get that that's a simplistic way to say it and you've got to be careful about sending too high a signal into the amp that way, but let's just say that we're being careful and that whatever the amp is passing to the connected headphones/speakers isn't going to hurt them or our ears.
@Andykong
Sorry, you might have missed my question, Andy, but I was hoping you could share the "factory recommended setting" about this^
You can't bypass the volume or any circuit in HA-300 by turning the volume all the way up. There is no by-pass feature in HA-300. If you must include a pre-amp in a HA-300 based setup, you have no choice but to live with double amping. For this reason, there is NO factory recommended setting.
There is no setting or procedure that will always work fine, we just have to find out the best compromise by audition, experience and trial and error. Some of the pre-amp will only deliver maximum 4Vrms or 8Vrms from their line out, but I have also run into some preamp that deliver over 20Vrms. Take
THIS preamp as example:
"The LA4's balanced output doesn't clip (ie, when the THD+N reaches 1%) until a very high 24V. Reducing the load to a punishing 600 ohms reduced the maximum output level to 15V (fig.4), which is still much higher than will be needed to drive a power amplifier into clipping"
In addition, the output of your HA-300 varied a lot when you change between L, M and H impedance setting. Take a look at the following table:
The rated output power of HA-300 are 7.59V at Low impedance, 18.17V at Mid impedance, 39.42V at High impedance. So when you switch from Low impedance to High impedance, the maximum output power of the amplifier will increased by over 500%.
Without knowing the specification of your preamp, line out level of your source, and impedance of your headphones, I simply can't offer any suggestion to make sure "whatever the amp is passing to the connected headphones/speakers isn't going to hurt them or our ears".
There is a safe method, but won't necessarily the good sounding method.
- Connect your DAC to HA-300 directly without preamp, test your headphones under different impedance setting, record the volume setting of each headphone, and select the LOWEST setting as the "safe volume setting" on HA-300
- Connect your DAC to preamp, and preamp output to HA-300, set HA-300 at "safe volume setting" and adjust the volume of the preamp to achieve the required output level.
This is safe, and it will work fine if your headphones are not vastly different in power requirement. Naturally if you have a headphone that sounds good at 8 o'clock volume position and then you have another headphone that sound good at 3 o'clock position, your more demanding headphone probably will sound very dull even when your pre-amp can offer enough output to compensate the low volume setting at HA-300. But you probably understand why it is impossible to recommend a "factory recommended setting" as requested.
