Buy the Denon AVR-X1800H for most rooms — it's $51 cheaper as tracked today and its power rating is the honest one. The Onkyo TX-NR6100 earns its place only if you need its stated 4–16Ω impedance rating for low-impedance speakers.
As tracked by Home Theater Builder: the Denon AVR-X1800H states 4 HDMI 2.1 ports; the Onkyo TX-NR6100 states 3.How we verify this data →
The spec sheets make this look like a mismatch: Denon claims 80W, Onkyo claims 165W. It's the clearest measurement-context lesson in our catalog — the two numbers were produced under completely different conditions.
Shaded rows differ · green dot = lab-measured · amber = manufacturer-verified · blue = retailer/community-reported · grey = estimated · “not stated” means exactly that
Reading the numbers honestly
Onkyo publishes ONLY a 165W figure measured into 6Ω with one channel driven at 1% THD — the generous way to rate an amplifier on every axis (easier load, single channel, ten times the distortion threshold). It states no 8Ω rating at all in our normalized data. Denon's 80W is at 8Ω, two channels driven, 0.08% THD. Under identical conditions the gap mostly evaporates: these are the same class of amplifier wearing very different stickers.
Compatibility · computed, not written
Checked against a bookshelf that dips to a stated 3.7Ω like the KEF Q150: KEF Q150
Can the Denon AVR-X1800H drive the KEF Q150?
Denon AVR-X1800H states a 4Ω-minimum rating; the KEF Q150 dips to a stated 3.7Ω minimum, a little below that floor. Most receivers handle a marginal dip at normal volumes — it's worth watching only at very high output on an entry-level unit.
Can the Onkyo TX-NR6100 drive the KEF Q150?
Onkyo TX-NR6100 states a 4Ω-minimum rating; the KEF Q150 dips to a stated 3.7Ω minimum, a little below that floor. Most receivers handle a marginal dip at normal volumes — it's worth watching only at very high output on an entry-level unit.
Computed from the catalog's normalized fields — the same fields the builder's compatibility engine reads. A missing field reads as "can't check", never as a pass.
Gaming & connectivity · answered from the spec sheets
How many HDMI 2.1 ports do the Denon AVR-X1800H and Onkyo TX-NR6100 have?
Denon AVR-X1800H states 4 full-bandwidth HDMI 2.1 ports; Onkyo TX-NR6100 states 3. Full-bandwidth ports are the ones that carry 4K/120 and VRR — the count that matters for wiring multiple current-gen consoles.
Can the Denon AVR-X1800H and Onkyo TX-NR6100 pass 4K/120 through?
The Denon AVR-X1800H states 40 Gbps HDMI bandwidth — enough for full 4K/120; the Onkyo TX-NR6100 states 40 Gbps HDMI bandwidth — enough for full 4K/120.
The verdict
Buy the Denon AVR-X1800H for most rooms — it's $51 cheaper as tracked today and its power rating is the honest one. The Onkyo TX-NR6100 earns its place only if you need its stated 4–16Ω impedance rating for low-impedance speakers.
Onkyo's headline 165W is 6Ω / ONE channel driven / 1% THD, and it publishes NO 8Ω rating at all in our normalized data — the honest read against Denon's 80W (8Ω/2ch/0.08%) is that they're much closer than the stickers suggest.
The Onkyo states a 4–16Ω speaker-impedance rating (4Ω-speaker friendly); the Denon states none.
Both carry HDMI 2.1 — 4 stated ports on the Denon vs 3 on the Onkyo.
Tracked prices for both are on this page — $849 vs $900 today; the receiver with the bigger power sticker is also the more expensive one.