Have you actually listened to the Starsea? The switches do change the sound signature for sure, this is even shown on graphs below. Changes in one segment eg bass, will affect the perception of the mids and treble and vice versa (AKA see saw effect).
This is in contrast to some other "tunable" IEMs I've tried like the NiceHCK M6 which has gimmicky stock tuning filters.
Graphs courtesy of KopiOKaya (IEC711 compliant coupler). 7 ā 8 kHZ area is probably a resonance peak.
With both switches down ā
āexquisite pure toneā ā The tonality sounds like a mild V shape with an upper mids and treble boost, with a slight bass boost. The bass is slightly north of neutral, subbass > midbass in quantity. It is quite comfortable in the higher frequencies and balances a fine line between shoutiness and a forward upper mids/lower treble. With louder volumes (Fletcher Munson curve), or in poorly recorded materials, then some shoutiness may show. Lower mids are depressed but not overly so like some other deep V shaped CHIFI sets. The treble is moderately extended here.
With switch 1 down, switch 2 up ā
ābeautiful vocalsā ā overall, upper mids are boosted, but the bass is decreased. Hence the ears perceive it to be somewhat bright U shaped. Thereās sibilance, and the upper mids and treble can get hot (due to the corresponding bass drop). Vocals are clearer, especially female vocals, though this tuning can get fatiguing with longer sessions due to the wealth of details and clarity. It has slightly less bass than the first āexquisite pure toneā config and approaches neutral in the midbass. Subbass quantity is still more than midbass, but subbass extension isnāt very deep and sounds like a BA bass in terms of speed and extension/decay.
Both switches up ā
ābalanced tuningā ā sounds like a mild U shaped. Indeed it is the most balanced of the configs as claimed. I think it is the most inoffensive of the tunings. It is probably the tuning that is quite similar to the big brother TRI I3, though the TRI I3 has a 3 kHz peak, but the peak in this configuration in the TRI Starsea has been shifted a bit earlier to the 2ish kHz region. This tuning has the thickest lower mids of the 4 tuning configs. Bass is north of neutral but not at true basshead quantities, especially when not amped/inappropriate source pairing. Treble is not the most extended here, trebleheads may find it overly safe.
With switch 1 up and switch 2 down ā
āamazing bassā ā sounds mild V shaped approaching L shaped, lower mids are recessed with a subbass boost. Upper mids and lower treble are boosted, but less than the bass, so the ear takes the frequency response as a whole and it is the most bassy of the 4 configurations. Subbass extension is the deepest of the 4 tunings here. But subbass is not the deepest in extension compared to other DD containing basshead IEMs. Bass is north of neutral, subbass is more than midbass in quantity but this is not at basshead levels even though it is claimed to be āamazing bassā. When not amped, or with wrong source pairing, I find it lacking a bit in midbass punch and thickness (in note weight), but then again, Iām a basshead so YMMV. The midbass thickness and quantity does improve with amping, using low output impedance sources, using narrower bore tips or perhaps copper cables (if you aināt a cable skeptic). Instead of pursuing a basshead quantity, TRI has gone for a good quality bass. Thereās no midbass bleed and quite good texturing present. The bass is on the speedier and tighter side. On this tuning, the higher frequencies are rather tamed, smooth and non fatiguing.