Aside from being comfortable to use in bed while laying on your side, in ears have another key advantage over headphones and that is bass response. While not as powerful, the bass produced by in-ears is deeper because with headphones the bass quickly dissipates before reaching your eardrums whereas with in ears the bass frequency doesn't have to travel since it's already in the ear canal. This is why using the correct ear tip for a proper seal is so strongly emphasized.
The overall sound of in-ears comes down to the driver setup, materials used and size of the drivers. The Hifiman RE-600S V2 are made with lightweight materials inside and out, including titanium diaphragms, aluminum accents and plastic, which is used for the shell of the earphones.
The total weight of the RE-600S V2 is just 17 grams, including the cable which for wired earphones is extremely low.  The low weight allows the RE-600S V2 earphones to sit on the ears comfortably and relatively secure despite the straight nozzle design. For anything like walking the dog or commuting to work, the earphones should stay in without falling out.
The 1.25 meter-long cable that comes with the RE-600S V2 earphones has an interesting sleeve construction made partly with rubber and braided fabric material, which spans most of the length of the cable (87cm) from the connector plug to the Y splitter junction of the cable.
The braided fabric cable sleeve is fairly thick and so is the Y plastic splitter which is sturdy. The internal wiring is covered by two shields, one which is made of mono-crystal copper and the other made one made of mono-crystal silver. The dual shielding of the RE-600S V2 cable provides EMI shielding so, the audio signal is more protected against interferences, including "microphonics", which is a particular issue that happens to wired earphones when the earphone cable rubs against something.
The 3.5mm gold-plated TRS connector features two green rings, instead of the usual black rings and it's attached to a thick straight plug. The RE-600S V2 don't integrate a microphone; hence the 3.5mm connector only has three sections, instead of four sections like a TRRS connector does.
Being wired earphones, the impedance rating is a factor since it will determine whether you can drive the earphones from a phone or whether you will need a headphone DAC to amplify the audio. The RE-600S V2 earphones have a low 16 ohms impedance rating, which means the DAC inside your phone should be able to deliver enough amplification to power the RE-600S V2 earphones to full fidelity. The RE-600S V2 speaker drivers have a high, 102dB headphone sensitivity, which can be appreciated from the video below.
With such high sensitivity and fairly large loudspeaker transducers, the 8.5mm drivers inside the RE-600S V2 are able to deliver loud volume effortlessly. The high frequencies and midrange are smooth, clear and free from imperfections even at max volume.

There are different types of ear tips included with the RE-600S V2 earphones so, it's worth experimenting with them to get the best of the audio you listen to, particularly songs with bass. While the sound filters do help with the bass, foam ear tips are also a good way to increase the bass response with in ears.
The sleak carry case folder that is included with the RE-600S V2 Earphones is made of leather-like material. The carry case folder has the size of a small book, measuring 23cm long, 14cm wide and 4cm tall and, weighing 286 grams.
Both the ear tips and earphones come neatly protected in foam square blocks. For daily use, the carry case folder can be a bit cumbersome to carry around, although a small, non-branded hard-shell zip pouch is included, which makes carrying the RE-600S V2 much more conveniently.
Included also with the RE-600S V2 earphones is a cable management rubber block that looks like a white chalk stick. The cable management rubber block weighs 6 grams and, it is deigned to neatly wrap around the cable of the earphones when not in use.