SPL Phonitor x vs SPL Phonitor xe

Short answer

More power: the SPL Phonitor xe, with 2.70 W into 32 Ω; the SPL Phonitor x has 1.00 W (balanced: 700 mW against 700 mW). The SPL Phonitor xe drives 1 headphone to 100 dB that the SPL Phonitor x cannot (Symphonium Titan).
Hiss with sensitive IEMs: no headphone here hisses audibly on one and not on the other.
Price: the SPL Phonitor xe costs $200 less and gives up nothing on power, output impedance or hiss against the 567 headphones here. Whatever the extra money for the SPL Phonitor x buys, it is not these three numbers.

Both are desktop amplifiers, $3200 against $3000.

The SPL Phonitor xe reaches 100 dB on 567 of the 567 models here, the SPL Phonitor x on 566.

Side by side

Every published figure, next to each other

Specification	SPL Phonitor x	SPL Phonitor xe
Power into 32Ω	1.0 W	2.7 W
Power into 150Ω	3.1 W	3.7 W
Power into 300Ω	4.2 W	4.2 W
Power into 600Ω	2.1 W	2.1 W
Output impedance	0.18 Ω	0.18 Ω
Output noise	5.48 µV	5.48 µV
Price	$3200	$3000
Headphones it reaches 100 dB on out of 567	566	567

Balanced output

The 4.4 mm or XLR socket, rated on its own

Balanced	SPL Phonitor x	SPL Phonitor xe
Socket	balanced	balanced
Power into 32Ω	700 mW	700 mW
Power into 300Ω	2.9 W derived	2.9 W derived
Output impedance	0.36 Ω	0.36 Ω
Output noise	9.75 µV	9.75 µV
Headphones it reaches 100 dB on out of 567	566	566

Through the balanced sockets the two are level on the same test: each reaches 100 dB on 566 of the 567 models here. Derived figures are worked out from the loads the maker did publish.

How solid these numbers are

Where each power figure comes from

Load	SPL Phonitor x	SPL Phonitor xe
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Derived	Derived
600 Ω	Derived	Derived

Both makers publish a power rating. SPL Phonitor x publishes at 32 Ω; SPL Phonitor xe at 32 Ω. The other rows are worked out from those.

The two publish at the same loads, which is the one case where the rows of this table can be read straight across.

What the labels mean.

What separates them

The headphones that tell them apart

1 headphone reaches 100 dB on the SPL Phonitor xe but not on the SPL Phonitor x — Symphonium Titan.

566 of the 567 models here reach 100 dB on both.

On real headphones

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Shure SE846: SPL Phonitor xe has +43 dB of headroom there against +38 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.

Hiss below about 20 dB SPL is inaudible in a quiet room.

Headphone	Impedance	Needs	SPL Phonitor x headroom	SPL Phonitor xe headroom	SPL Phonitor x hiss	SPL Phonitor xe hiss
Shure SE846	9 Ω	0.04 mW	+38 dB	+43 dB	29 dB	29 dB
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+18 dB	+23 dB	9 dB	9 dB
Audeze LCD-2 Classic	70 Ω	0.79 mW	+33 dB	+35 dB	7 dB	7 dB
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+39 dB	+39 dB	3 dB	3 dB
HiFiMAN HE400se	25 Ω	7.9 mW	+20 dB	+24 dB	2 dB	2 dB
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+32 dB	+32 dB	-4 dB	-4 dB
Sennheiser HD 600	300 Ω	6.6 mW	+28 dB	+28 dB	-8 dB	-8 dB
HiFiMAN Susvara	60 Ω	50 mW	+15 dB	+17 dB	-10 dB	-10 dB

What the price difference buys

The gap in dollars, against the gap in numbers

The SPL Phonitor x costs $200 more than the SPL Phonitor xe, and on these three axes the money buys nothing: among the 567 models here there is not one that the SPL Phonitor x handles and the SPL Phonitor xe does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper SPL Phonitor xe drives one model to 100 dB that the SPL Phonitor x does not.

Only published figures count here; blank axes are counted separately.

Each in full: SPL Phonitor x and SPL Phonitor xe.