Burson Soloist 3X GT vs SPL Phonitor xe

Short answer

More power: the Burson Soloist 3X GT, with 4.00 W into 32 Ω; the SPL Phonitor xe has 2.70 W (balanced: 8.00 W against 700 mW). Both drive 567 of the 567 non-electrostatic headphones here to 100 dB, so on that test the difference changes nothing.
Hiss with sensitive IEMs: no headphone here hisses audibly on one and not on the other.
Output impedance: 1 headphone is left alone by the SPL Phonitor xe under the one-eighth rule but coloured by the Burson Soloist 3X GT (Symphonium Titan).
Price: the SPL Phonitor xe costs $201 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are desktop amplifiers, $2799 against $3000.

On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.

Specification	Burson Soloist 3X GT	SPL Phonitor xe
Power into 32Ω	4.0 W	2.7 W
Power into 150Ω	650 mW	3.7 W
Power into 300Ω	320 mW	4.2 W
Power into 600Ω	160 mW	2.1 W
Output impedance	0.5 Ω	0.18 Ω
Output noise	1.5 µV unverified	5.48 µV
Price	$2799	$3000
Headphones it reaches 100 dB on out of 567	567	567

Specification

Burson Soloist 3X GT

SPL Phonitor xe

Power into 32Ω

4.0 W

2.7 W

Power into 150Ω

650 mW

3.7 W

Power into 300Ω

320 mW

4.2 W

Power into 600Ω

160 mW

2.1 W

Output impedance

0.5 Ω

0.18 Ω

Output noise

1.5 µV unverified

5.48 µV

Price

$2799

$3000

Headphones it reaches 100 dB on
out of 567

567

The 4.4 mm or XLR socket, rated on its own

Balanced	Burson Soloist 3X GT	SPL Phonitor xe
Socket	XLR4	balanced
Power into 32Ω	8.0 W	700 mW
Power into 300Ω	640 mW	2.9 W derived
Output impedance	0.5 Ω	0.36 Ω
Output noise	not published	9.75 µV
Headphones it reaches 100 dB on out of 567	567	566

Through the balanced sockets the Burson Soloist 3X GT reaches 100 dB on 567 of the 567 models here and the SPL Phonitor xe on 566. Derived figures are worked out from the loads the maker did publish.

Where each power figure comes from

Load	Burson Soloist 3X GT	SPL Phonitor xe
32 Ω	Published	Published
150 Ω	Published	Derived
300 Ω	Published	Derived
600 Ω	Derived	Derived

Both makers publish a power rating. Burson Soloist 3X GT publishes at 32 Ω, at 150 Ω and at 300 Ω; SPL Phonitor xe at 32 Ω. The other rows are worked out from those.

So the two columns are not equally firm row by row: at 150 Ω and at 300 Ω only the Burson Soloist 3X GT figure is the maker’s own. On those rows the derived number is the one to doubt first.

What the labels mean.

The headphones that tell them apart

On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.

1 headphone is left alone by the SPL Phonitor xe under the one-eighth rule but coloured by the Burson Soloist 3X GT (Symphonium Titan).

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

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Sennheiser HD 600: SPL Phonitor xe has +28 dB of headroom there against +17 dB. 11 dB is about 13 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Burson Soloist 3X GT because that maker publishes no output noise figure.

Headphone	Impedance	Needs	Burson Soloist 3X GT headroom	SPL Phonitor xe headroom	Burson Soloist 3X GT hiss	SPL Phonitor xe hiss
Shure SE846	9 Ω	0.04 mW	+48 dB	+43 dB	not published	29 dB
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+28 dB	+23 dB	not published	9 dB
Audeze LCD-2 Classic	70 Ω	0.79 mW	+35 dB	+35 dB	not published	7 dB
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+28 dB	+39 dB	not published	3 dB
HiFiMAN HE400se	25 Ω	7.9 mW	+27 dB	+24 dB	not published	2 dB
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+21 dB	+32 dB	not published	-4 dB
Sennheiser HD 600	300 Ω	6.6 mW	+17 dB	+28 dB	not published	-8 dB
HiFiMAN Susvara	60 Ω	50 mW	+17 dB	+17 dB	not published	-10 dB

The gap in dollars, against the gap in numbers

The SPL Phonitor xe costs $201 more than the Burson Soloist 3X GT. Out of the 567 models here, that difference buys 1 more model left alone under the one-eighth rule.

Nothing runs the other way: there is no axis here on which the cheaper of the two does better.

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