It is the only proper way to drive HPs directly off speaker output. You have to be careful with volume, switching, cable pulling and the like - no resistor in series to absorb and protect from anything what should not be there in the first place. Power levels and HP sensitivities have to be reasonably matched, both for HP safety and hiss reasons. Far from all speaker amps are quiet enough with all HPs, particularly IEMs. But they are out there.
Once you experience a good combo of speaker amp driving suitable cans, you will find it hard to go back to more normal setups. If you are looking for euphonic result or are using some HPs that are known to sound beter with high(ish) amp output impedance, this might not be the ticket. Anything else -
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You may discover that volume potentiometer on (vintage) amp/receiver is iffy at lower volume setting compared to speakers. How much a really good reliable pot costs - sky is unfortunately the limit here. But a decent blue Alps unit should be good enough for all but most extreme situations and most demanding users. Better spending for say an Alps than having to replace costly HPs due to the fact that pot can trough intermittent contact al lower setting output full blast the amp is capable of.