I have a UR44 with a couple of XLR input mics which seem to work fine.
However, if I plug an iPhone or PC audio into a line in port, the audio quality through the headphones is very poor and tinny with very little bass.
I have tried turning up the gain for the line in channel but it doesn’t make the quality any better, and there doesn’t appear to be any settings in dspMixFx to fix this.
Loopback audio and music via the USB connection sounds fine, it’s only line in that is bad.
Is there a way to make the line in audio sound better?
Hey Steve,
I presume you are referring to Line Inputs 5+6 on the rear of the UR44?
First up, have you swapped out the lead from iPhone/PC (presumably a stereo mini jack to 2 mono 1/4" jacks) to check it’s not the lead?
If the lead is ok, is the poor sound only from the a headphone output (headphone output 1, 2 or both) or is it also from the main outputs of the UR44?
I have a UR44 so I could try and replicate the problem if you provide specifics about cabling, set up etc.
Cheers
Stevo… 
EDIT
A quick follow up. I have a Roland Fantom G plugged into Line Inputs 5+6 and when I have the UR44 connected by USB to my laptop, I get a horrible digital background noise. The noise gets worse during disk access and screen updates.
However, replacing the mono (unbalanced) 1/4" leads with stereo (balanced) leads eliminates the noise issue. 
I then tested the output from both my Samsung S7 phone and iPad2 using a mini stereo jack that splits to two 1/4" mono jacks into inputs 5+6 of the UR44.
The sound from both the main and headphone outputs were clean, clear and as expected.
I did have a faulty unit from new (as were many due to bad components) and my UR44 was from the first batch released, having been on pre order 3 months before release.
The fault was hissing, crackling and a very low input level on channels 1+2 but I would have thought that all new(er) UR44 units would not contain the problematic components. Still, worth a mention.
Would be good to hear if you resolve your problem.
Cheers
Stevo…