Here's a longer double-header: I compared the Symphonium Giant ($700) and Titan ($1000) for about a week. Both are bassy sets with completely different tunings: Giant is warm warm warm, while Titan is clear and energetic with massive subbass rumble.
Symphonium takes a less-is-more approach to driver count, and a more-is-more approach to power requirements. The Giant features a single DD + BA with 88 dB/mW sensitivity and 7Ω impedance, while the Titan packs a DD + 2BA configuration with an extremely low 80 dB/mW sensitivity and 3Ω impedance - the lowest sensitivity I've ever seen in an IEM by a long shot. This thing drinks current like a thirsty sailor. Thanks to AudioGeek EU for the chance to try these on tour!
Titan
I listen to my Kiwi Ears Punch a lot, and I liked the Titan for many of the same reasons. It's got nice tonality and clarity through the mids and treble, with some sparkle, and vocal tone sounds correct. That's complemented by a crazy bass boost that doesn't bleed into the mids, but gives a very fun subbass rumble. This is, without question, a basshead set. In spite of that, this is easily the best vocal presentation I've heard yet from Symphonium (vs Giant and Crimson, which I found a bit nasal and shouty, respectively).
If you've listened to other bassy sets and thought "no, this isn't enough physical rumble," the Titan could be just what you're looking for while still performing admirably beyond just the bass. It gives more subbass rumble than Kiwi Ears Punch, with a touch less warmth through the mids and more forward upper mids and treble. The treble has a bit of spice which helps balance against the bass, but I don't find it fatiguing.
With the subbass focus, the bass doesn't give the super fast, snappy feel that more conservative subbass tunings generally give, but it performs very well. It keeps good separation from the mids, not compromising clarity. The separation and resolution is also very good - it kept the busy double-kicks and bass line well defined in Death's "Moment of Clarity" and really shone with electropop like Charli xcx's "B2B" with huge bass synth hits.
Giant
The Giant offers a big midbass thump with impressive bass rumble and good punch, but not nearly as much subbass compared to the Titan. The star of the show here is strictly bass - lots of it, gliding unabashedly through the mids making the whole presentation warm. The presentation is more relaxed rather than engaging, with vocals taking a step back in the mix. Male vocals sound a bit nasal, and while there's no sibilance with smooth treble, it's lacking edge and sustain on cymbals.
Comparison
The Giant is warm and midbassy with smoothed out, recessed vocals and treble, while the Titan is more energetic with better vocal timbre and huge subbass but less warmth and body to instruments. Treble sparkle comes through with the Titan but not on the Giant.
The shells are small, light, and very nicely built, though the triangular shell shape doesn't work too well for my ears, creating a hotspot by pushing on my tragus. It's worth trying a Symphonium IEM first to see if this shell shape works for you. Giant is a bit smaller than Titan.
For my preferences, the Titan is the clear winner. I find it a really enjoyable basshead set that brings very fun bass with impressive subbass rumble while maintaining good clarity and technical performance throughout. It's easy to recommend if you're looking for a bassy set. The Giant didn't quite work for me, but if you're looking for a warm bassy set and don't mind vocal and treble presentation that could euphemistically be called "analog," it's something to consider.