Flat frequency response is desirable but I don't believe it's the most important factor in sounding live. Dynamic linearity(linear changes in loudnes from micro to macro) is absolutely necessary. Change a seat in a live concert and frequency response changes but both seats sound alive. Or stand by a door outside a room and it's far from flat response but if it's live in the room you know it and it it's reproduced sound you know it too. Flat response is wonderful but secondary.
Do YOU have a flat frequency response in your room?
The most basic truth of audio for the last 30 years is listeners prefer a flat frequency response. You achieve that through getting the right speakers, in the right position, in the right room, and then use room treatments and DSP to dial it in. If you are posting questions about what gear to buy and have NOT measured your room and dialed it in to achieve a flat frequency response FIRST you are blowing cash not investing cash IMO. Have you measured the frequency response in your room yet and posted it?