Out of the box I knew Mojo2 was special ...so I immediately applied my isolation kit to discover its ultimate sound quality. All I can say is wow! Rob Watts appears to have incorporated all his genius into this little marvel and Mojo2 returns huge benefits (like other Chord DACs) by pushing the limits of isolation. Here's what I recommend to get Mojo2 to sound its very best ...by which, I mean, maximally transparent.
- Use external (software) upsampling. The upsampling logic inside Mojo2 is very good but software upsampling has the edge in nuance and realism. PGGB 256 is my choice for the absolute best reconstruction quality. 256 bits of precision and maximal (unlimited) taps extracts insane transparency but it requires offline pre-processing of local tracks. For on-the-fly (real-time) streaming, choose HQPlayer or PGGB-RT (foobar only).
- Use Battery operation. Mojo2 has a terrific battery based power supply that's good for several hours. For my testing I didn't use the battery bypass desktop mode but instead configured a DC power switch to disconnect Mojo2 from the RF noisy AC/DC charger during playback. Minimal hassle for best sound ...but I will explore external 5V power options. I also recommend using LFP battery power for ultra low noise DC and AC as required.
- Use DBNC input. Dual BNC is the ideal way to get the most transparency from a Chord DAC. Avoid USB input to reduce clock and gate switching noise from the USB receiver chip. I used my product chain: USB•FILTER > Ferrite filtered USB cable > SRC•DX > LP•FILTER > DC•BLOCK to a Mojo2 3.5mm adapter assembly. Set the playback bit depth to 24-bits and set the same on the PGGB or HQP noise shaper.
- Use Efficient headphones or an external head-amp. The Mojo2 has a powerful internal amp - but driving inefficient headphones increases current demands and (IMO) reduces the magic effortlessness we want to hear. So, IMO its best to use line level output. I used efficient HE1000se's and an external preamp/head-amp with 50kOhm input impedance to deliver a much more authoritative sound - and it also extends Mojo2's battery life to well over 8 hours.
Then consider the next steps if you really want to be amazed:
- Optically isolate the DBNC signal input. Stop RF noise at the Mojo2 signal input with OPTO•DX and RF•STOP Extreme DC Power Filters (from an LFP battery).
- RF•STOP Signal Filter at the output. Use a 3.5mm to RCA stereo adapter/patch cable (I use both Mojo2 outputs) to my new analog signal filter. This stops downstream RF noise from coming back into Mojo2.
- DAC•WRAP magnetic shielding. Mojo2's will sound its best when its small signal processing is least perturbed from environmental magnetic fields.
- Avoid Mojo2's cross-feed and equalization feature. Mojo2's 104 bits of EQ precision does improve low/high end linearity and timbre but, unfortunately, transparency suffers. If you must, use PGGB_EQ for true lossless EQ. Similarly avoid the cross-feed feature.
In my next blog I'll do a Mojo2 & Dave comparison!
