I'm having trouble with my studio monitors (headphones as well). They are JBL 104s, which are pretty affordable entry level speakers. I've got a handful of headphones, typically between 32 ohm and 64 ohm.
It came with a 3.5mm TRS to 2x RCA, which connected fine to my standard PC output (Realtek ALC892) and also worked with a cheap USB headphone DAC (Fiio K1).
I'm not sure what spec is relevant to this, but the USB DAC is 100 dB SNR for reference. The Realtek ALC892 seems to be 95 dB SNR.
It seemed fine at first, but I typically had to set the volume knob at 60% minimum. The volume seems low in general, and I'm not sure if this is normal. I routinely have to go to 60-80% volume. And I noticed the speakers produce some form of harmonic distortion at high volume levels, which is absolutely not acceptable for mixing as it's making me see clipping where there is none.
I'd prefer if the monitor provided sufficient output at around 30-50% volume level.
I ended up getting a PCI-e soundcard, Sound BlasterX AE-5 Plus. Albeit intended for gamers, it seemed to have a better DAC than my onboard or even my Fiio K1. It even had ASIO drivers (although, they seem to be a bit buggy). The soundcard's DAC has a 122 db SNR. This translated to my speakers being slightly louder, although not as much as I would have liked. Significant harmonic distortion still occurred around 80% volume on the JBL speakers.
When connecting headphones to my JBL monitors, they were significantly quieter compared to my headphones being connected directly to the soundcard. This was a bit troubling, as it seems to imply a sort of "de-amplification", i.e., signal strength is lost somehow.
So I'm not sure if it's these specific studio monitors that are just not good, or if I need some sort of dedicated audio interface with a proper pre-amp. I've looked at the Focusrite Scarlett 2i4, but it's USB powered entirely; is that really enough to pre-amp a professional studio monitor and headphones simultaneously?
Are my expectations unrealistic, or am I just not paying enough for proper gear? Does using balanced audio cables instead of unbalanced make a big difference?
I'd appreciate a technical explanation of any sound concepts related to what I'm noticing, such as SNR, gain, amplification, THD or anything else.