• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

What I've learned so far and its application (HD650 D70 HPA V90)


Addicted to Fun and Learning
Forum Donor
Aug 14, 2019
Sweden, Västerås
Hi there time for some feedback.

What I've learned so far and its application (HD650 D70 HPA V90).

Some references .

Windows settings advice.

My headphones. Senheiser HD650




The Headphone AMP is Violelectric HPA V90 their entry level offering (discontinued)

There is also a RaspPI Picoreplayer and some Fostex desktop monitors.

The story here.

I was upgrading my computer and also considering where i should do my headphone listening previously my HD650 was sitting in a corner with the HPA V90 and a RasPI with a HAT DAC and not seeing much use.

Then some things come together in my mind . I've seen the test on my headphones and several other test they pointed to the importance of EQ to get good sound even out of headphones ? I previously I naively assumed as there is no room acoustics involved that headphones should just work :)
And then the tread about windows also hinting about Equalizer APO and give me some more understanding of current windows ( I previously mostly used Linux on my old desktop, now I'm using windows only ) . That good sound is pretty straight forward .

My new headphone rig is thus.

Topping D70 (non mqa it was on sale at audiophonics ) this one is new for me.
My Violelectric HPA90
One of my RaspPI with a new digital out HAT (this is used when the PC is off its connected to my LMS music server that runs the rest of the house).

How it all goes together .

On the PC i use Foobar and JRiver they are set to use 24/192000 for everything.
I also use Spotify and Squeezelite X but there i let windows do the sample rate conversion.
Windows is set to output 192000 .

I let all the players use the windows audio system so that i can use Equalizer APO for all audio and also shut off "original APOs" (se windows tread).

The results .

I can use my headphones for music and normal windows duties and gaming and YouTube and Netflix no fussing with WASAPI or ASIO exclusive . with as good sound as possible :) win.

I can now explore Headphone EQ both in Foobar2000 but mostly in Equalizer APO I'm learning a lot by doing this . I'm experimenting with Amirs suggested eq settings and Oratory1990 settings and some others and making fine adjustments by my own.

The HPA V90 has some useful features . It has input gain settings I,m at -6dB now because the EQ takes some headroom ( you can have -12,-6,+6,+12 dB )
This together with the very quiet Topping D70 and the HD650 makes a system with almost no noise I've never heard the almost total absence of hiss its unnervingly good :)

The HPA V90 has another very useful feature buffered pass trough of the analog signal this feeds my desktop monitors , some small fostex.
Next project use REW to cobble together speaker EQ to use with Equalizer APO.

Equalizer APO. has a features that makes it fast and easy to switch EQ as you wish.

And if the PC is off i can still listen to my music server with speakers and headphones , ofcourse with no EQ ( RasPI is connected to the coax input. )

Thanks for a great forum where you actually can put the pieces together .


Addicted to Fun and Learning
Forum Donor
Aug 14, 2019
Sweden, Västerås
The HPA 90.

Inputs: 2 x Cinch, unbalanced
Max. Input Voltage: + 21 dBu, Impedance 10 kOhms
Input Impedance: 10 kohms
Buffered Outputs: 2 x Cinch unbalanced
Nominal Input Sensitivity: +6 dBu
Amplifier Overall Gain: +8 dB
Overall Gain with PRE-GAIN: -4 / +2 / +8 / +14 / +20 dB
Frequency Range: 0 Hz ... 55 kHz (- 0,5 dB)
0 Hz … 200 kHz (-3 dB)
Damping Factor: > 300 into a Load of 50 Ohms
Dynamic Range: > 126 dB (A-wtd)
Noise: < -102 dBu (A-wtd)
THD+N (1kHz/2x10V/100R = 1W) < -108 dB / < 0,00035 %
THD+N (1kHz/2x4V/32R = 0,5W) < -102 dB / < 0.0007 %
Crosstalk: -110 dB (1 kHz) / -90 dB (15 kHz)
Top Bottom