OK… This was somewhat surprising for me. I now have a much clearer understanding of the advantages and disadvantages of both the ISN H40 & the Fiio FH3. The biggest surprise was that when I thought I had the general gist down of their characteristics and was attempting to guess at how each would perform on the next track, many times I was wrong until I actually listened back to back.
Here are my listening findings
ISN H40 VS Fiio FH3
AMP NOTES & TIPS
DAC - SMSL SU-8
AMP - THX AAA 789 on low gain
Running the ISN H40 4.4 balanced (this may give the H40 a slight advantage)
Running the FH3 unbalanced 3.5
TIPS
ISN H40 - SpinFit CP100-S
Fiio FH3 - SpinFit CP100-M
The ISN H40 would probably benefit from an analytical amp/dac while the Fiio FH3 would benefit from a warmer amp/dac.
All my sources are FLAC USB direct to DAC.
GENERAL FINDINGS
FR on both sets is quite similar. Technicalities show their differences better than FR.
H40 - More natural timber, softer, slower, warmer, easier to drive (balanced), can be sibilant on certain tracks, really shine with acoustic/romantic/emotional music.
FH3 - Incredible technicalities espcially overall detail, bass & mid control, and speed. Upper frequencies are smooth! Incredible stage and image seperation. Timber can be slightly tinny at times. Tracks need to be recorded very sibilant to show on the FH3.
BASS
Big Boi - Boomiverse - Kill Jill - FH3 WIN - Sub bass is more textured and defined on FH3
Hyper - Lies - Lies - FH3 WIN - Bass is more textured and defined on FH3
Blade Runner 2049 - Original Motion Picture Soundtrack - Wallace - H40 WIN - Ambient Sub Bass with dynamics, H40 sounded more dense
Tool - Fear Inoculum - Legion Inoculate - TIE
SPEED, TRANSIENTS, DYNAMICS & TEHCNICALITIES
Dream Theater - Distance Over Time - At Wit’s End - FH3 WIN - Much tighter, faster & detailed
Jason Richardson - I - Titan - FH3 WIN - Much tighter, faster & detailed - This is a TORTURE TEST
Hyper - Lies - Spoiler - FH3 WIN - Much tighter, faster & detailed
Interstellar - Original Motion Picture Soundtrack - Mountains - TIE - No clear winner for dynamics test - FH3 more detailed, H40 warmer/softer
Daft Punk - Random Access Memories - Within - H40 WIN - Softer, warmer and more romantic, timber of ride was warmer, “tinnier” on FH3.
Opeth - Watershed - Porcelain Heart - H40 WIN - Softer, warmer and more romantic, timber of ride was warmer, “tinnier” on FH3.
SOUNDSTAGE & IMAGING
Yosi Horikawa - Wandering EP - Letter - FH3 WIN - Much wider and much better imaging hands down. H40 feels maybe half as wide as the FH3.
Tool - Fear Inoculum - Legion Inoculate - FH3 WIN - Much wider and much better imaging hands down.
TREBLE SHARPNESS
Darkwater - Human - Alive (Part II) (guitar solos) - WOW! This was telling - FH3 WIN - FH3 not only wins hands down for the guitar solo harshness, the image definition and clarity were bad on the H40. Everything smeared together. It sounded like a mess compared to the FH3. The ride sounded more natural/warmer on the H40 where the FH3 sounded more tinny.
FEMALE VOCALS/SIBILANCE/TEXTURE/MIDS
Adele - Hello - H40 WIN - Warmer, more romantic, softer, more natural timber
Aurora - A Different Kind of Human - FH3 WIN - FH3 is smoother and not sibilant, H40 can be sibilant.
Big Boi - Boomiverse - Kill Jill - H40 WIN - H40 treble is more aggressive, FH3 is smoother
Paramore - Riot - crushcrushcrush - H40 WIN - This was CLOSE! Both sets get sibilant, I preferred the body and warmth of the H40 more.
Evanescence - Fallen - Bring Me to Life - FH3 WIN - FH3 is smoother and not sibilant, H40 can be sibilant.
Dua Lipa - Future Nostalgia - Don’t Start Now - TIE -
Colbie Callat - Breakthrough - Droplets - H40 BIG WIN - Softer, warmer and more romantic. The H40 really shines here. Beautiful!
White Moth Black Butterfly - Atone - Rising Sun - FH3 WIN - Vocals are clearer and not as pushed back as on the H40
Sabrina Claudio - Confidently Lost - Tell Me - H40 WIN - Softer, warmer and more romantic. Can be on the edge of sibilant.
Amaranthe - Amaranthe - Amaranthine - FH3 WIN - FH3 is smoother and not sibilant
Diana Krall - Turn Up the Quiet - Night and Day - H40 BIG WIN - Softer, warmer and more romantic. More natural timber shines here.
MALE VOCALS/TEXTURE/MIDS
Daniel Tompkins - Castles - Castles - FH3 WIN - H40 was constantly sibilant. FH3 was smooth.
White Moth Black Butterfly - Atone - Rising Sun - FH3 WIN - Vocals are clearer and not as pushed back as on the H40
Eumeria - Rebel Mind - Rebel Mind - FH3 WIN - Vocals are clearer and not as pushed back as on the H40 surrounding instruments sounded mushy.
James Labrie - Elements of Persuasion - Drained - FH3 WIN - Vocals are clearer and not as pushed back as on the H40 surrounding instruments sounded mushy.
Ghost - Prequelle - Pro Memoria - H40 WIN - Softer & warmer.
Evergrey - The Inner Circle - A Touch of Blessing, More Than Ever - FH3 WIN - Vocals are clearer and not as pushed back as on the H40 surrounding instruments sounded mushy.
Opeth - Damnation - Windowpane - H40 WIN - Softer, warmer & more natural timber
Opeth - Watershed - Porcelain Heart - H40 WIN - Softer, warmer & more natural timber
Ray Alder - What The Water Wants - The Road (Acoustic) - H40 WIN - Softer, warmer and more romantic.
Symphony X - Iconoclast - When All Is Lost - TIE - H40 for the acoustic/slow portions, softer, warmer & more natural timber. FH3 for heavier parts. FH3 is clearer and vocals are not as buried as H40.
John Mayer - Room for Squares - My Stupid Mouth - FH3 WIN - FH3 is smoother and not sibilant. H40 was horribly sibilant on this track, wanted it out of my ears!
REQUESTS
Nubiyan Twist - Straight Lines - H40 Vocals are pushed back vs the FH3. Generally warmer timber. Bass is almost in the way of other instruments. FH3 has a claner presentation. Prefer the FH3 generally on this track.
My choice…
EDIT: Photos added.