The little boxes that were used with computers, that have a built-in amplifier in the speaker could be worth a go, preferably the mains powered ones, the battery ones use C or D cells and are a bit heavy on the batteries. I feel that the ones you are talking about for 40 quid may not have a built-in amp, and I think for a tone control of any sort to work, you need extra gain as can be supplied only by an amplifier. SOME of those have treble boost switches and controls.
Years ago, when I was still an apprentice, I bought myself a pair of (newly released) Sennheiser stereo headphones. Everyone who listened to them was amazed. The model, as I recall, was HD414. My brother was newly working for the only local commercial AM radio station, and when he showed them to his management they were so impressed, within six months every radio station in the network and probably the country had standardised on them. They were a bit vulnerable in the plugin cables, but they used coarse texture foam rubber earpads, so you could still hear what was happening around you. I recently excitedly bought a wireless pair of the same brand at a garage sale but I was VERY disappointed, they seemed to be a VERY poor pair of headphones with a receiver added. The radio station later bought HD424, a later model, I didn't like them so much. I always made sure I had a spare pair of foam rubber pads and a spare cable for mine - if you tripped over the lead it would have been history. There was a connector into each earphone (with gold plated pins) but the cables were something like what we called "tinsel flex" - like a fthin flat-section wire wrapped around a piece of string. Makes it extremely flexible but a bit vulnerable. With our hot summers in Rockhampton, the foam rubber pads would let you down without much warning.
