Home Audioquest PowerQuest 707 – 505 and 303

Audioquest PowerQuest 707 – 505 and 303



  • Clear impact on sound
  • Nice form factor
  • Plenty of outputs


  • Low Current outputs could be better
  • PowerQuest 303 somewhat up-front
Build quality
PowerQuest by Audioquest

Measurements and conclusion


We measured the Audioquest PowerQuest 707 in our lab. We did those measurements directly in the wall and with the help of a programmable AC generator. And we used a LISN to see what goes back to the mains. Last but not least, we measurement at the output of the Bryston PowerPAC 300 amplifier. It turned out to be an interesting session with a somewhat unexpected outcome!

Filter test – in the wall

The test “in the wall” shows a similar outcome as with the generator. But here we can test well with and without an interference source. The PowerQuest shows that it really does push noise away after all. Is all the noise gone? No. But we now know that almost no filter does that. But the fact is: noise is reduced.

It is striking that the Low Current output seems to have higher noise than no filter. However, we see that the interference of the dirty amplifier between 1000 and 5000 Hz is much more suppressed than no filter. Above that we see it rear its head again.

The High Current output handles this a lot better. Overall it is really quieter than the Low Current. In the listening test this was also audible.

Filter test – at the generator

The generator was not so happy with the “battery” in the 707. We were getting some warnings and beeps. And the fan immediately went to fighter jet mode. Anyway: it kept working, so we quickly took measurements.

We see that High Current filters more than Low Current. Weird: we expected it the other way around. Low Current also has a “bulge” that we’ve seen before with the previous measurement. We can’t explain that.

The PowerQuests have no DC blocking circuit we see. The injected white noise is attenuated, but not completely eliminated. We see that the 707 does indeed filter very effectively from 30 KHz onward. There everything falls down quickly.

Filter test – amplifier output

Here we see the slight but constant impact on the speaker output. It is subtle, but constant. We can also see here that the Low Current filters differently than the High Current. Around 1500 Hz, the Low Current pushes out more noise than the High Current. But overall, the High Current is a bit more constant, we estimate.

Noise on the mains side

We see a clear shift in noise between the standard unfiltered socket and the PowerQuest 707. With the 707, overall the noise drops and we see less impact from the dirty switching amplifier. It’s not gone – nor can it be: a filter shifts noise – but it’s definitely less.


Audioquest has launched a nice trio with the PowerQuest series. Now we find the 303 less interesting than the 505 and 707. Purely because the 303 does not filter in common mode, which is a crucial point nowadays. The 505 does and the 707 adds the 'reservoir'. Both steps are audible in calmness, balance and imaging.
Type test
Production country
  • Brand and model: PowerQuest 303
  • Build quality: Basic, but fine
  • Overall impression: Bit up front
  • Price: €599
  • Brand and model: PowerQuest 505
  • Build quality: Basic, but fine
  • Overall impression: Nice balance, much better than 303
  • Price: €799
  • Brand and model: PowerQuest 707
  • Build quality: Basic, but fine
  • Overall impression: Nice balance, calmness and fluidity
  • Price: €1299
  • Winkels met Audioquest

    Sint-Antoniusstraat 15
    2300 Turnhout, BE
    Joseph Bensstraat 21
    1180 Ukkel, BE
    Pleinweg 136
    3083 EP Rotterdam, Zuid-Holland, NL
    Hooikade 13
    2627 Delft, Zuid Holland, NL
    Bredabaan 1031
    B-2930 Brasschaat, BE
    Pelikaanstraat 126
    2018 Antwerpen, BE
    Schoenmakersstraat 19
    6041EX Roermond, NL
    Grotestraat 23
    5931 CS Tegelen, NL
    St. Ceciliastraat 28
    5038 HA Tilburg, NL
    Geldropseweg 105
    5611 SE Eindhoven, NL
    Breestraat 146-148
    2311CX Leiden, Zuid Holland, NL
    Korte Jansstraat 11
    3512GM Utrecht, NL
    Korevaarstraat 2 e-f
    2311 JS Leiden, NL
    Koningsstraat 35
    2011TC Haarlem, Noord Holland, NL
    Theresiastraat 151 - 157
    2593 AG Den Haag, Noord Holland, NL
    Beethovenstraat 9-b
    1077 HL Amsterdam, Noord Holland, NL


    1. Aloha Jaap, I recently purchased the 707 for protection more than filtering, but I was wondering would you recommend connecting a Grimm MU2 to the high power side with an amplifier? I’m not sure if the switching mode power supply would affect the amplifier more than it was plugged in on the far low power side? Thank you for your great work. Mahalo!

    2. I don’t know what you think Jaap , but I have to say looking at the Price :
      It seems to me that for a system up to 3000/4000€ the powerquest 2/3 (200/300€) are really really good for the price. Of course Niagara or powerquest 503 might be better but we’re talking about double the price or about 800/900€ instead of 200/300€