Can a DAC sort out a flat\cold amp?

@orenm145 I concur with many others that have already stated that the amp is not the problem

In the interest of problem isolation, if you have not already done so, may I suggest you simply your build for a moment and validate the source of the problem

Take the PC and network out of the equation

What happens when you play the tuner, are you happy with the bass?

If so move up the food chain and connect an external CD player to the Yamaha and test

Those two tests should confirm if the amp is part of the problem

Best of luck

"A gross lack of bass is NOT characteristic of that amp or any properly functioning modern HiFi SS amp..."

With due respect, I disagree with this statement here.  The disparity of treble, midrange and bass sound signatures among all types of amp. could be highly significant.  This applies to Yamaha as1200 without exception.  Listening to several reviewers such as Tarun (a british audiophile) and Andrew (Robinson), they both point out as1200's bass is nimble, textured but not as weighty/full as compared to several noteworthy competitors.  It has been well-known the Yamaha amplifiers were relatively leaner sounding in the bass region and that was why I start up my 2-channel hi-fi system with the Harmon Kardon Integrated amplifier 25 years ago.  Don't get me wrong, the higher end Yamaha amplifier like this does shine in its high-end frequency clarity which produces very transparent / detailed treble. But as a compromise, this clarity also extends into its midrange which also produces leaner sounding compared to its peers.

Given that sound signatures of the amplifier, it is difficult for a DAC to mitigate its leaner performance in midrange or bass.  While noticeable refinement can be expected, a complete make-over that changes the sound signatures of a amplifier is less likely.  That is why I was suggesting a cost-effective solution with Hegel Integrated amp.  Don't take my words for it.  I am just translating my previous experience to the OP so he could make more informative decision.

Thanks for all the help & insights. unfortunately I don't have many options. I have a bigger room but it has a huge glass window which won't be ideal for the vibrations in higher volumes. investing in sound dampening is not a good idea since I will probably move from this apartment in about 6 months. I'm aiming to find a good balanced equipment that I can go forward with & replicate the setting in different locations with similar room sizes. changing the table is also not viable option. the speakers are front ported so I figured it's not that bad & they performed well with my old amplifier although it was under a DSP mode which was like loudness button combined with virtual surround. It wasn't true to the source & some audiophiles will call it blasphemy but the only one that need to love the sound is me so...

Tone controls do help but are individual for each recordings which can take away from the laid back & easy listening.  Also it changes something else regarding the general feel of the sound which i can't really point out maybe narrowing of the soundstage & losing separation & detail retention. The pc power supply is sitting at the bottom so i'm less worried about that. I'm starting to think may be i just need to add a sub to the mix & not rely on the towers alone. the DAC , sepakers, room , cables , cord... everything could be better but i think this is a more elementary problem. low level listening is basically non existent unless i turn the bass all the way up.

As i mentioned before i'm living in a difficult country in terms of deals , trades & second hand parts If i was to sell this i would get 1000$ & they will try to lower the price some more even though i only have this for less than a year. I lost alot of money buying equipment & trying to repair it after it failed few months down the line. Basically second hand equipment is a huge gamble here & also the repairs & restoration are really low level work borderline a scam (some even got to the courtroom)  so I was better off buying something new then dealing with second hand parts. I triple checked the phases it's pretty basic red to red white to white. the cables & interconnects are blue jeans cables & it's good enough for me. I was considering the schiit bifrost 2 but i'll do more research about the DACS suggested here. about the reviews the top end did calm down with the break in but the low end did not extend with it just stayed the same. 

The reason i thought a DAC will help is A.my DAC is not a dedicated HIFI DAC B. i listen to very lossy audio (youtube\soundcloud) & could get alot of benefit from upscaling & upsampling C. when I listen to a good source like a real 320kbps the bass problem diminishes significantly D. this amp does not come with a DAC so it's pretty much mandatory.

bobby1945

i'm not going to build a room dedicated to audio. i'm not at that point in my audiophile journey. getting the speakers from the wall will require changing the table. my pc is ok it's just an old case. here's a Picture so you can calm yourself.

crustycoot

I do get bass but at volumes too high for my liking. the seat situating in a null created by room acoustics may be an angle i need to investigate further. 

after reading all the comments I think this situation will require a sub which is something i tried to avoid cost wise.

The amp itself can’t be the problem unless it’s defective. Yamaha integrateds always have strong bass, no reason an amp wouldn’t. Here is a review that mentions the bass being too strong: (skip to "The Listening" 2nd paragraph)
https://www.stereonet.com/uk/reviews/yamaha-a-s1200-integrated-amplifier-review

Nor should a soundcard be the problem; any soundcard from 25 years ago can play music fine. Except in the case that its software or some other software on your PC has auto calibrated for the amplifier in some gross way.

Check your wiring to speakers and amp, your software, and your amplifier’s manual.

edit -- if you really need to confirm your room isn’t the problem is there another space you could take the amp and speakers briefly? Also, as somebody already said, try with just a CD player, game console, etc bypassing the PC. -- sorry for redundancies, your last post came in while I was writing this.