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Here's my advice: try out the new MK5 Etymotic just released last month. For me, it was a very clear step up in audio quality compared to the HF series. To me, the quality of Etymotic's historical lineup ranges ER4S > ER4P/PT > ER6/i > MK5 > HF5 > EK > MC5. I'm frankly a bit surprised they're only selling for $60. Give them a spin and see if your impressions are similar, you can't go wrong for the price. They also have better, though similar, build quality to the HF series.
Overall the MK5 sound is a lot clearer and more detailed than the HF5, though the MK5 goes for a wide soundstage while the HF5 goes for an intimate in-your-face one. One big thing to note is that the MK5 have much tighter, more present bass, compared to even the ER4 line (and no it's not boomy in any way whatsoever, it's still an Ety). It sounds quite a bit like the old ER6 with a touch less microdetail and a wider sound stage.
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