I am not so sure it is the Sony, but to be sure you have to diagnose properly, excluding one possibility at a time. Going through the chain from the beginning:
1 it could be the actual music. Listen to a live symphony orchestra, and at times that can sound pretty harsh. Use classical music as a source to judge this. Solution if there still is a problem and if this is the cause: face up to reality.
2 it could be the mastering. These days many pop recordings are mastered at very high levels, with clipping distortion as a result. This is intended, even of not necessarily by the original artists in case of a modern remaster. In that case the cure would be to get hold of anolder mastering. With classical music this is rarely a problem.
3 it could be a mismatch between signal levels of the analogue source and the analogue input, potentially generating clipping distortion. Many amplifiers cannot quite handle the high 2.0 volt (or more) signal levels of e.g. a cd player. This could also happen with digital sources, but less likely. Cure: an inline attenuator in the case of an analogue source, or a reduction in the digital domain (if possible). Question: do you suffer this harsh sound with all sources (including FM radio, or only with some?
4 Jitter from the inbuilt DAC of the Sony (if you are using the digital input). I doubt it will be as serious as your problem seems to be. Cure: a different receiver.
5 insuffient power, leading to clipping of the power amplifier. Hard to imagine in such a small room.
6 harsh speakers. I don’t know these speakers, but changing them around with some other speakers will identify if they are the culprits. Cure 1: get other speakers. Cure 2: use your amplifier’s tone controls.
7 a harsh sounding room. If your room has too many hard and reflective surfaces, use damping materials like rugs etc to dampen those reflections. If that is not enough, use the tone controls. Compare the sound when using the same gear in a different room.
Beyond this, have a close look at the settings of the receiver. This is a fancy piece with more options than you can imagine in your wildest dreams. And therefore more possibilities to get it wrong. Make sure you know what you are doing.
Reading about your own experiments, it looks as if the combination of speakers and the room is the real culprit.
You do not mention it, but in a small and square room such as this, the subwoofers are also likely to generate a lot of nasty room modes at the lower end. Just two small high quality mini monitors may well give a much better sound (or move all this gear to a bigger room in the house). This room really is too small. If you insist, use the room eq in the receiver, if you have not already done so. But in such a small room, room modes will be at pretty high frequencies (up to the room’s Schroeder frequency of 245 Hz or so for the fundamentals, and much higher for the harmonics), and equalization will only work over a pretty small listening position. Do not think using just one sub wil work: it will only make matters worse because multiple subs even out the response.
If you want to measure what you are hearing, get a UMIK-1 calibrated microphone and measure with the free REW software (unless the Sony allows you to do about the same).
1 it could be the actual music. Listen to a live symphony orchestra, and at times that can sound pretty harsh. Use classical music as a source to judge this. Solution if there still is a problem and if this is the cause: face up to reality.
2 it could be the mastering. These days many pop recordings are mastered at very high levels, with clipping distortion as a result. This is intended, even of not necessarily by the original artists in case of a modern remaster. In that case the cure would be to get hold of anolder mastering. With classical music this is rarely a problem.
3 it could be a mismatch between signal levels of the analogue source and the analogue input, potentially generating clipping distortion. Many amplifiers cannot quite handle the high 2.0 volt (or more) signal levels of e.g. a cd player. This could also happen with digital sources, but less likely. Cure: an inline attenuator in the case of an analogue source, or a reduction in the digital domain (if possible). Question: do you suffer this harsh sound with all sources (including FM radio, or only with some?
4 Jitter from the inbuilt DAC of the Sony (if you are using the digital input). I doubt it will be as serious as your problem seems to be. Cure: a different receiver.
5 insuffient power, leading to clipping of the power amplifier. Hard to imagine in such a small room.
6 harsh speakers. I don’t know these speakers, but changing them around with some other speakers will identify if they are the culprits. Cure 1: get other speakers. Cure 2: use your amplifier’s tone controls.
7 a harsh sounding room. If your room has too many hard and reflective surfaces, use damping materials like rugs etc to dampen those reflections. If that is not enough, use the tone controls. Compare the sound when using the same gear in a different room.
Beyond this, have a close look at the settings of the receiver. This is a fancy piece with more options than you can imagine in your wildest dreams. And therefore more possibilities to get it wrong. Make sure you know what you are doing.
Reading about your own experiments, it looks as if the combination of speakers and the room is the real culprit.
You do not mention it, but in a small and square room such as this, the subwoofers are also likely to generate a lot of nasty room modes at the lower end. Just two small high quality mini monitors may well give a much better sound (or move all this gear to a bigger room in the house). This room really is too small. If you insist, use the room eq in the receiver, if you have not already done so. But in such a small room, room modes will be at pretty high frequencies (up to the room’s Schroeder frequency of 245 Hz or so for the fundamentals, and much higher for the harmonics), and equalization will only work over a pretty small listening position. Do not think using just one sub wil work: it will only make matters worse because multiple subs even out the response.
If you want to measure what you are hearing, get a UMIK-1 calibrated microphone and measure with the free REW software (unless the Sony allows you to do about the same).