The talk of current amplifier vs voltage in audio?
Many audiophool beliefs have no basis in fact, and this one is no exception.

Normal commercial loudspeakers are meant to be driven with a voltage signal, not a current signal.

You are probably thinking "But what's the difference?  Whether I'm controlling voltage or current into a 8 &Omega; load, I get the same thing."  That's true, but the gotcha is the speaker presenting a nice and constant 8 &Omega; resistance is the ideal, not reality.  There will be inevitable impedance changes as a function of frequency.  These are due to the significant inductance of the speaker coil, and various mechanical resonances.  The proverbial 8 &Omega; impedance is just a rough number that speaker manufacturers aim for but never achieve perfectly.

Given that the impedance of the load varies, you have to decide what the real signal is, voltage, current, or something else.  In this case voltage was picked for good reason.

When a frequency hits a resonance of a speaker, the impedance goes up.  With constant voltage as the impedance changes, the power into the speaker is inversely proportional to the resistance.  That means at resonance, less power is transferred to the speaker.  That's a good thing, because due to the resonance, the speaker will produce more sound for the same input power.  The lower power going into the speaker won't offset the whole frequency peak caused by the resonance, but it helps at least somewhat.  This also works in reverse for dips in the frequency response where the impedance goes down and the speaker becomes less efficient.

With fixed current into a varying load, the power is proportional to resistance.  That will make the uneven frequency response of a speaker even worse in most cases.

Even if without understanding the above mechanism, it should still be obvious to use a voltage signal since that's what the speaker was designed for.  Lots of engineering goes into the design of high end speakers, with significant effort to make the frequency response as flat as possible given the other constraints of size, cost, and the like.  The design strives for constant sound output power for fixed input voltage across frequencies.  This can and inevitably does come at the expense of flat frequency response for a fixed input current.

Current drive is simply not what the speaker was designed to work with.  When you run anything out of spec, you can't expect it to perform within the remaining specs.