Sorry to hear your crackle etc. I have not experienced this. For me, I can hear a very faint buzz if I put my ears 1" away from my coaxial drivers. Was told it could be some line noise but I never bothered to filter it (lack of time!), its also present with my IDA6. So I assumed its my line or a characteristic of NuP.
Did you check your connections/banana plugs etc. I have seen loose connections doing funky things
I have not been able to get rid of the buzz. Will update with a recording later this week. This was not present on the IDA-8 with exact same options.
Description of buzz: It's faint and not audible to my ears at listening distance (8 ft from each speaker). It is audible few inches from the speaker cone.
I am in the process of renovating my basement with sound proofing/ sound absorption so will update once this project is complete.
Listed below are the options tried:
1. Swapped USB cables from computer to AMP.
2. Tried on different Laptops WIN as well as MAC.
3. Changed power supply.
not sure if this will help but in the Q&A it talks about downloading the latest firmware
Look under HT.
Still haven't been able to get AIRPLAY to work.
I downloaded the folder with the FW but was unable to update. Menu navigation is the shortest path to frustration, it is buggy beyond comprehension.
If anybody has successfully attempted the FW update I would appreciate if you could please share your tips. Attached here are some screen captures of both menu and FW folder & file path
Review of the musicality of the AMP:
The AMP is definitely more musical sounding than the IDA-8. There is a sweetness to the sound that is easily discernible to even non-audiophile ears. I did multiple blind tests playing the same music vis-à-vis the IDA-8 when playing through the USB-DAC. Bass is definitely more pronounced, tight and fulfilling at lower volumes. The sound stage is well described & detailed. Vocals are rich and full throat'd(if that makes sense). Tracks:
1. Pink Floyd: Wish you were here
2. Ed Harcourt: The cusp and the wane
3. Raghu dixit: Preetiya Hesare Neenu (Unplugged version)
4. Muddy Waters: Hoochie coochie man