The Sonnet Echo 21 Thunderbolt 5 SuperDock is a fantastic port and storage expansion for new Mac users, and isn't pinched for bandwidth.
We get a lot of docks in for review. A lot.
In many cases, we see docks with a lot of ports, but they connect over 10 gigabit per second USB-C. Worse, downstream ports are listed as providing that same 10 Gbit/sec.
That will never work. You can't expect two USB-C devices using 10 Gbps connections to run at full speed when the connection to the host is also just 10Gbps.
Even with Thunderbolt 3 and Thunderbolt 4, the bandwidth of 40Gbps to the host is a lot, but that too can be saturated with enough high-bandwidth peripherals.
Add storage, and it gets even sketchier.
Long time dock maker Sonnet has has delivered the second dock in its Thunderbolt 5 catalog with the Echo 21 Thunderbolt 5 SuperDock. Lots of ports, lots of speed, and the potential for a lot of storage.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Physical design
The Echo 21 isn't a massive departure from your typical dock design. It's a rectangular block of metal, emblazoned with the Sonnettech logo on the top.
There are hints of fins on the top, but they seem more useful for grip than for any sort of real cooling ability beyond flat aluminum. That said, it does have a fanless design, so it runs silently.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Front port selection
At 9.6 inches long by 4.2 inches, it doesn't have a big footprint. With a thickness of 1.3 inches, it's something that could also be tucked away for a cleaner desk setup.
There's also the power brick to contend with, which measures 2.9 inches by 6.1 inches and 1 inch thick. This, as well as the combined weight of the dock and brick of 2.9 pounds, makes it a lot less portable than a MacBook user would actually want.
Also in the box is a power cord, as a first, an acceptable length 2.5-foot Thunderbolt cable, and a ThunderLock-A connector.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Connectivity
As the 21 part of the name implies, there are a lot of connections onboard, split across the front and back.
To the front are ports intended to be more directly used by the user, including a pair of USB 3.2 10Gbps Type-A ports, three more in Type-C form, a combo headphone jack, and UHS-II SD and microSD card reader slots.
Around the back is the lion's share of ports, including the Thunderbolt 5 host port with 140W of power delivery. There are two more Thunderbolt 5 ports for peripherals, though daisy-chaining isn't provided here.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Massive rear port selection
The back also has video ports for DisplayPort and HDMI, a 10-Gigabit Ethernet connection, two more USB 3.2 Type-A ports, and two more USB 3.2 Type-C ports. There's also a separate microphone jack and line-out RCA jacks for connecting to speakers or other audio equipment.
The Thunderbolt 5 interface works at 80Gbps for bi-directional data, though it can also work with the standard 120Gbps display mode too.
When it comes to video support, it can handle up to four displays, depending on what the connected Mac is able to support. At its most extreme, the dock can deal with a 4K 60Hz monitor on the HDMI using HDMI 2.0b, or a 4K 144Hz monitor on DisplayPort 2.0.
The dock is also compatible with the iPad Pro. However, you will only be able to have one mirrored or extended display supported by the dock.
Aside from the host port, the other USB connections provide power at 7.5W, with one USB-C on the front singled out to provide 15W. This seems ideally located to connect a MagSafe charger or for direct USB-C charging of an iPhone while the user works.
Overall, the dock supports Thunderbolt 3, 4, and 5 devices, USB hubs, USB 4 and USB 4v2 devices, and monitors, as well as USB 3 and earlier peripherals.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Storage and speed
The Echo 21 Thunderbolt 5 SuperDock is actually the stablemate of another, the Echo 20 Thunderbolt 5 SecureDock. And by stablemate, we mean twin, since the two models are almost exactly the same.
The only difference is that the Echo 21 has a storage feature, while the Echo 20 does not. The Echo 20 is intended for corporate or government organizations wanting the dock functionality but without added storage for security purposes.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: Storage space
The storage in the Echo 21 is made up of an internal M.2 NVMe SSD socket in the base.
An internal M.2 NVM2 SSD socket provides storage
According to Sonnet, that drive section can operate at up to 3,300 megabytes per second, and also supports Time Machine backups.
In our testing that speed claim was accurate with PCI-E 4 SSDs. With a PCI-E 3 SSD, we saw about 2600 megabytes per second read and write.
In April 2026, you don't need to, and shouldn't, pay PCI-E 4 or 5 costs for this dock. That can be a $100 difference on even lower capacities, and since the port won't hit those 6000 megabyte per second speeds, it's not worth the extra.
We tested how the dock responds to the Mac sleeping too. The dock stays active through this sleep, which is different than cheaper USB-C docks.
What that practically means, is a keyboard connected through the dock will wake the connected Mac. And, more importantly, under macOS 26.4 with a Thunderbolt 5 host, we didn't get any badly-disconnected drive warnings either.
We did get those warnings, though, when connecting to any Thunderbolt 4 or USB4 host, even with Power Nap off. We're not sure why, probably something about how Thunderbolt 5 works, versus the older protocol, but it's a nice addition.
Sonnet Echo 21 Thunderbolt 5 SuperDock review: An almost bottleneck-free dock
As a Thunderbolt 5 dock, the Sonnet Echo 21 is less affected by a bottlenecked connection than others. Under the right conditions, you can still bottleneck it, but the sheer bandwidth available in Thunderbolt 5 means you'll have to do a lot to hit it.
This upper ceiling has allowed Sonnet to go nuts, providing users with a ton of expansion options, with them running at or near full speed in parallel. Sure, a lot of it is USB-A and USB-C centric, but you'd expect a lot of peripherals to be using those connections.
Having a pair of RCA jacks is an unexpected addition to an already extensive connection selection. But adding storage on top is a big move too.
That all said, the entire package does get a bit pricey. It's $499, which is quite a lot for someone to pay for a dock, but the connectivity justifies the price.
For power users wanting a Thunderbolt 5 dock, this one provides plenty of options for what you can connect to your Mac. Possibly more than anyone would reasonably want.
All without any real worry of anything you connect to it slowing down.
I like this dock a great deal. Sonnet has always provided excellent hardware for the Mac, and has for decades at this point. The Echo 21 is no exception to that rule.
However, if you're looking for a dock, consider Sonnet's Echo 13 Thunderbolt 5 dock. Sure, there are fewer ports, but for $479, you get 1TB of faster storage included.
Sonnet Echo 21 Thunderbolt 5 SuperDock pros
- Huge number of ports
- Fast NVMe storage
- Thunderbolt 5 speed
Sonnet Echo 21 Thunderbolt 5 SuperDock cons
- High cost at $499
- Plain design
Rating: 4 out of 5
Where to buy the Sonnet Echo 21 Thunderbolt 5 SuperDock
The Sonnet Echo 21 Thunderbolt 5 SuperDock is available from B&H Photo for $499.99.
