I have used this DAC almost exclusively via USB; my original computer (Mac Studio) was earthed; when I replaced with an unearthed computer (Mac mini), I heard 50Hz hum on the Sony DAC since the Sony has no earth (it can only operate floating with the devices which are connected to it).
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Juson Audio JTA100 200W Tube Amplifier Vacuum Valve BT5.0 Hifi Stereo USB RCA Opt Remote Phono Headphone 2.1CH for Turntables
Aliexpress UK
FULLY Working but has aFaulty Headphone Socket. Headphone socket only outputs to ONE ear when wearing headphones, Everything else works as it should.
eBay
Class A Portable Headphone Amplifier Fever-grade High-thrust HIFI Headphone Power Amplifier Large-capacity Battery 2134 Op Amp
Aliexpress UK
Condition: Used.
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Class A Gold Sealed Tube Headphone Power Amplifier 4.4mm Balanced Output 2000mW Power Desktop Headphone Amplifier MUSE02 Op Amp
Aliexpress UK
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BGGQGG 16-300 ohm HiFi Headphone Earphone Amplifier 3.5mm Jack Aux Portable Adjustable Audio Amp for Mobile Phone Music Player
Aliexpress UK
Used -Excellent.
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16-300Ω HiFi Headphone Earphone Amplifier 3.5mm Jack Aux Portable Adjustable Class A Audio Amp for Mobile Phone Music Player
Aliexpress UK
Power output: 60 watts per channel into 8Ω (stereo). This has been tested and is in full working order. It is sold with a 3 month warranty. Signal to noise ratio: 90dB (MM), 105dB (line). Damping factor: 100.
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Fosi Audio T20X MKII BluetoothTube Amplifier 150W*2 Class D Stereo Power Amp For Home Theater Speakers Headphone
Aliexpress UK
Plus, superior picture quality to match with 4K HDR pass through. Bluetooth with standby for instant connection and 4 Analogue inputs. Phono Input for connection with turntable.
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HA-6A HIEND Tube Headphone/Earphone Amplifier with 4.4mm, 6.35mm and XLR Phone Output. EL34/KT88 Switchable
Aliexpress UK
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Ear Pads Headphone Earpad For SONY PS5 PlayStation PULSE 3D EarPads for sony Headphone Earpad Replacement Cushions Cover Earmuff
Aliexpress UK