Cover the XPS 16 with the XPS 14 speaker tuning

Reported to suit the XPS 16 as well, so the tuning now matches both machines and
the directory is named for the pair rather than the one model.

Gating moves from the DMI product name to the product SKU, which is what Dell keys
the Cirrus speaker firmware on -- 10280db9 for the XPS 14, 10280dba for the XPS 16
-- so it identifies the speaker hardware itself instead of a marketing name. SKUs
are compared as whole values, not substrings, so this cannot widen to the rest of
the XPS line the way a short product-name match would: product_family on these
machines is "Dell Laptops".

match_sku and match_dmi are now lists, letting one tuning name every model it
covers. A plain string still works as a single entry.

The measurements in tuning.conf were taken on the XPS 14 (0DB9). The XPS 16 is
covered on report rather than measurement, and tuning.conf and the graph both say
so, because the profile's bass lift and high-pass were fitted against one
machine's excursion and distortion limits.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

default/audio/tunings/dell-xps-2026/filter-chain.conf

@@ -1,10 +1,13 @@
-# Dell XPS 14 DA14260 speaker tuning.
+# Dell XPS 14 / XPS 16 (2026) speaker tuning.
 #
 # Biquad chain fitted to the measured response of the xps-audio-linux EasyEffects
 # profile under a dense pink-weighted multitone of 104 bin-aligned tones,
 # followed by a lookahead limiter. Measures 1.24 dB RMS against that reference
 # (0.97 dB weighted over the fit's own error metric).
 #
+# Fitted and measured on the XPS 14 (SKU 0DB9); the XPS 16 (0DBA) is covered on
+# report that the same profile suits it. See tuning.conf.
+#
 # Q below 200 Hz is capped at 1.8 on purpose. A closer magnitude fit is possible
 # with high-Q sections, but the reference produces its narrow bass features by
 # convolution, and reproducing them with high-Q biquads swung group delay 31 ms

default/audio/tunings/dell-xps-2026/tuning.conf

@@ -1,15 +1,19 @@
-## Dell XPS 14 DA14260 internal speakers.
+## Dell XPS 14 / XPS 16 (2026) internal speakers.
 ##
 ## Thirteen biquads and a lookahead limiter, applied as a PipeWire filter-chain
 ## in front of the internal speaker sink. The stock Linux path already loads
 ## Dell's Cirrus smart-amplifier firmware; this adds the perceptual voicing the
 ## Windows Waves layer provides and Linux does not.
 
-description="Dell XPS 14 (2026) speakers"
-## Matched on the DMI product name plus the presence of the sink below, which
-## together are specific enough that no per-model predicate script is needed.
-## Hardware needing a sharper test can set match_command to any predicate.
-match_dmi="XPS 14 DA14260"
+description="Dell XPS 14/16 (2026) speakers"
+## Matched on the DMI product SKU, which is what Dell keys the Cirrus speaker
+## firmware on -- 10280db9 for the XPS 14 and 10280dba for the XPS 16 -- so it
+## identifies the speaker hardware itself rather than a marketing name. Compared as
+## whole values, so this cannot widen to the rest of the XPS line.
+##
+##   0DB9  XPS 14 -- measured here, see below
+##   0DBA  XPS 16 -- included on report that this profile suits it, not measured
+match_sku=("0DB9" "0DBA")
 ## Unescaped dots: this is passed to awk as a string, where a backslash escape
 ## would be consumed before the regex sees it.
 sink_pattern='^alsa_output.*sof_sdw.*HiFi__Speaker__sink$'
@@ -22,6 +26,10 @@ sink_pattern='^alsa_output.*sof_sdw.*HiFi__Speaker__sink$'
 derived_from="xps-audio-linux xps-clone (MIT, spencerbull)"
 validated_by="dhh"
 validated_on="2026-07-24"
+## The measurements below were taken on the XPS 14 (0DB9). The XPS 16 (0DBA) is
+## covered on report rather than measurement; re-measure there before treating
+## these figures as describing it.
+validated_hardware="XPS 14 DA14260 (0DB9)"
 
 ## Measured against that reference under a dense pink-weighted multitone of 104
 ## bin-aligned tones. See docs/AUDIO-TUNING.md for how to reproduce these.