Try a bunch of different tips, the sound and comfort will be different in every pair of ears. I try many tips over several weeks and eventually settle on one, JVC Spiral Dots, Comply foam and Sony triple comfort are my most used. Almost all of the most popular and easily obtainable tips fit the Sennheiser IEMs, the absence of that foam insert in the core doesn't seem to make a discernable difference.

I have several portable DAC/amps and dongles they each sound different. I don't doubt that some people don't discern a difference but that may be because they are unable to, not because there isn't one. I suspect that some of the differences won't be reflected in frequency response but they may be measurable in some other way. I get why some people rely on measurements but, those can also serve as a form of placebo, if it measures well by a certain standard they feel confident about buying it. I wouldn't recommend someone choose their first DAC/amp based on how people describe a particular device's sound though.

Have you tried using them outside at all? Open back headphones usually don't sound great outside if you can even hear them.

I don't care about measurements, they'll sound good or they won't. If I hadn't just bought a new Sony phone I would buy this Walkman.

BTR5 is a great sounding device, I used one daily for a couple of years. I used LDAC with my phone, sounds very similar to using the usb connection, I say similar because it isn't actually the same but I found it equally enjoyable. Mine is still in good condition with little loss of battery runtime. If you have an interest in EQ or think you'll enjoy tinkering with an extensive phone app, the Qudelix would be better for that, other than it's app its very similar to the other bluetooth DAC/amps.

Look for new music or go into a semi trance if I've timed my meds right.

Both Sony and Audio Technica make wired earphones with ANC, they seem to be more popular in Asia, they sell some in other markets but it seems to be limited to one or two models. Some sellers on Amazon list wired some earphones as noise cancelling but the ANC may only work with certain media players and cellphones. I think B&O had some ANC earphones in their Beoplay line.

You'll probably get used to it. When in ear headphones first became popular a few decades ago, many people had difficulty with hearing their own footsteps, pulse, voice etc including me. If you ignore it your brain tunes it out as useless info, bear in mind how popular IEMs and wireless buds are compared to traditional style earphones that don't have that effect.

You either have a faulty pair or they aren't sealing properly in your ears, the wf-xm4 have unusually good bass for TWS and they have very tame treble, I prefer them to the over ear wh-xm4. In the app there is a seal test, I think its in the third section of the app, try it out. I usually have the volume at about 50%, I never raise it over 60% as it starts to get uncomfortably loud, I don't have super acute hearing.

Purely by mood and whim.

I've been using Bluetooth DAC/amps for around three years, usually with LDAC or LHDC, I don't perceive a big difference from when the device is connected by cable.

I don't have the dt770, they should be a lot more demanding than the IEM I compared them to judging by the sensitivity and impedance.

I'm not sure what the output power actually is on the KA3 single ended socket but, I would expect your dt770 to be a stretch for it depending on your preferred volume. I used a Fiio BTR5 for a while with an IEM that has unusually low sensitivity, for an IEM, it was loud enough for me at 50% volume from the SE socket. This IEM's impedance was only 14 ohm, your headphone will be quite a bit more demanding. You could get an amp and feed it from the KA3, this is likely to be cheaper than buying a new DAC/amp.

I've been using the Spiral Dots for a while with various IEMs and really like them, I usually avoid wider bore tips as they can reduce bass and sound a little bright, they don't have that effect in my ears.

I think TWS can sound as good as IEMs but, there will always be people who will insist that wireless is trash whether they've tried Bluetooth at it's best or not. I often use IEMs with a wireless DAC/amp with LDAC, it sounds very similar to using a USB DAC, I find that the biggest factor in sound quality is the production of the music I'm listening to.

Roll a towel or blanket up and shape it into a ring, put head on it. There are pillows available for listening with headphones, I suspect that their original purpose is for sitting comfortably after certain types of surgery or childbirth.

The ear hooks just guide the cable over the ears, they don't support any weight, they're also referred to as cable guides. I just insert the IEM and bend the wire back over my ears with no particular care and then leave it alone, I don't try to make it match the shape of my ears as there is no reason to, it takes me no longer to fit them than an IEM with the pre-formed ear hooks. I imagine that wearing glasses with them will take a little longer to get them comfortable.

I'm getting a Neuromancer vibe from this, is she plugged into a Maas Neotek? I love it.

Great headphones for lively electronic music and rock, worth picking up Yaxi type B pads for them, pillowy comfort.

I'd be interested to know if you continue to enjoy it over the next few weeks and I hope that you do. I bought a similarly priced IEM a while ago and was very pleased with it, thought it sounded great. I used it daily for about a week then felt less and less like using it. I try it occasionally to try and identify what it is that makes it so boring, it remains a mystery. I had the same reaction to the Etymotic er2xr, sounds good but I get nothing out of listening to my favorite stuff with it.

I use Tidal at the moment, I was using Qobuz but often found that they didn't have the music I wanted. With a phone you also have to use a separate app called UAPP to ensure that music plays at the right sample rate through a DAC/amp and with decent volume. With Tidal you don't have to do that though you can if you prefer, Tidal can run in exclusive mode from the phone app. I enjoy using it quite a bit, they recommend stuff that I actually like rather than whatever is popular. They also show you how much of your subscription fee goes to artists and you can nominate an artist to receive it. I also use Bandcamp and Bleep to discover new stuff, I buy FLAC of my favorite albums from them.

I have the Sony wh-xm4 and wf-xm4 buds, when I've watched video on my MacBook with them they will connect with AAC, I don't notice any latency on YouTube or with streamed movies. With my phone I use LDAC at highest quality and don't notice latency with YouTube or streamed movies. I mostly use wireless DAC/amps with LDAC and don't get latency with those either. I don't play any games, I imagine that if there was going to be latency it would be with games.

You're probably better off not buying cheap Chi-Fi. I only have one ChiFi IEM, it was $300, its good though I never use it. The only IEMs I've had problems with were cheap ChiFi models that were very popular when I first got interested in them.

I use LDAC a lot and don't see latency with video. Some manufacturers make a big deal of their product supporting whatever the latest bluetooth standard is like 5.2 or 5.3 but, if they don't mention the codec it may only be SBC. AAC is usually decent but not all products will perform the same when using the same codec or BT standard.

There will be some 2.4ghz or similar receivers intended for use with instruments and for pro stage monitoring but, I've never used them. Try a store for musicians.