I've been meaning to try a USB Purifier
Yes, I only tried the 3.5mm Line-Out on the Gryphon cause I do not have a 4.4mm to RCA Cable (to pair the DAC to my Active Speakers). It's been some time since I sold the Signature (needed something more transportable) but going from memory, Signature was a bit more detailed, had a bit more width in the soundstage, sounded fuller (more bodied) & warmer. It drove Planars better. I remember reading somewhere that Signature has in-built iPurifier tech, so I guess that gives it an edge in filtering USB noise.
I actually think the Gryphon does a fairly good job managing interference and noise. It's only minor fault is the Amp noise with sensitive IEMs (which can be "fixed" with IEMatch). Mojo 2 on the other hand is a bit picky with USB sources.
Headphones tested (when comparing Gryphon & Signature): HiFiMan Sundara, Meze 99 Classic & Philips SHP9500
Oh, It seems mostly you compared both in Dac/ amps and those impressions are as Dac/amps, right?
If it is like that, then it sounds right, as Dac/Amps I have read signature is warmer and wider, I suppose some stage help due to power.
As far as resolution sense It seems it depends of the headphone, with planars I truly believe the Idsd could be better, due to pure amp power.
With other headphones, when both used as dac/amp and it is not a hard to drive headphone, especially dynamic ones, it seems more like a synergy thing or preference.
**But** all of this is speaking of both aa Dac/Amps.
No one seemed to do a tedious -Only Dac- VS between the 2.
I have read the 4.4 dac line out is better but can't confirm since I have not both cables for A/B.
And well, about the USB purifier thing.
You may get better results with a DDC than with the ipurifier.
I don't know why but as dac/amp the Gryphon showed more upgrades with the Breeze DDC than the ipurifier.
With the ipurifier it was like : 4%More vocal fullness in a good way/better vocals, tighter bass, cleaner sound overall.
Maybe overall a +5%, but things like Stage size do not changed.
With the DDC it clearly has an improvement in Stage size when used as dac/amp.
Overall I found it more impressive with the DDC but I returned my purifier and Could not compare both so take that on mind!
But I'm pretty sure about the Stage size.
I was comparing Ipurifier 3USB gryphon vs HRT microstreamer and that was LOTS of times, both had similar stage size when using the purifier.
The HRT received a very good upgrade in noise from the purifier.
In fact I loved the HRT+Purifier sound that I have been trying to get another Ipurifier( I can't use my DDC with it because hrt has no spdif and my ddc is toslink and coax only).
When using gryphon as DAC with the Soloist, I get a noticeably clearer sound when using the DDC.
But I don't notice like if the DDC made the stage bigger in that case( opposite to the Dac/Amp situation).
A guy I know says the Gryphon is close to the Bifrost 2 as DAC but I have not compared both.
And I'm still interested about how much help the Idsd can get with a DDC/Purifier and how they would compare to Gryphon as Dac/Amp and only DAC.
Next from me, if all goes well:
-TXCO Crystal DDC VS Ipurifier 3 as Dac/Amp.
-TXCO Crystal DDC VS Ipurifier 3 as Only Dac.
-TXCO Crystal DDC and Ipurifier 3 combined both dac/amp and only dac.
-4.4mm vs 3.5mm Dac Line out( some people said balanced outputs were cleaner, who knows lol)