A gross lack of bass is NOT characteristic of that amp or any properly functioning modern HiFi SS amp. Other than speakers wired with incorrect polarity (a definite possibility), an impedance mismatch (unlikely) or your seat is smack dab in a null created by room acoustics, I’m hard pressed to come up with another rationale for what you describe. A Schiit Loki may be your best bet if the other proposed solutions don’t provide an answer.
Can a DAC sort out a flat\cold amp?
My pc is connected to an external sound card (scarlett 2i4 by focusrite). I bought the Yamaha a-s1200 & am really disappointed at the brightness & the lack of bass to the extend I prefer listening to my portable JBL boombox. I'm in no position to sell or trade this amplifier so I thought a DAC with eq may help the predicament. Since auditioning my equipment is not an option in my country I have no choice but to buy something purely on recommendations. I also thought about replacing the speakers but since I listen to soundcloud & youtube i really think upscaling & eq will be much more cost effective option in sorting out this issue & may give me the confidence to try a much more expensive speaker option. what would you recommend?