what we normally don't get is that "hifi" means fidelity to the recording.
in that way, if the recording doesn't have "big bass", 2 thing can be happened:
1) the artist want the song in THAT way
2) the recording isn't good
so, a "hifi" amp won't reproduce great bass from that recording, and that's in the way it is.
normally, many "audiophiles" like the "bassy / warm" amp (tubes are great for that), but that's not hifi.
how can you cure that? EQ ... but applying EQ over a transparent amp.
well, making the story short ... a hifi amp will show what the recording have, nothing more, nothing less.
i don't know if this is the case, but check the recording first, and then see what amp is playing the real thing. That's the amp you need to use in a hifi system (and remember, you can add EQ, but not to delete it if it's inside the circuits).