[4] The duo gradually moved into less melodic and more experimental music, notably with the release of albums like Confield, Quaristice, and Exai.

[9] Brown and Booth have stated in interviews their newer music is primarily composed with something named "the system"; it has been described as a large network of synthesisers and digital processes built in Max.

[10] While Autechre make use of Max, and more specifically "the system", Booth stated the music wasn't entirely generative; it instead requires human input to change and guide tracks.

[13] Critics wrote that the composition of Sign was a lot more accessible in comparison to the duo's previous projects such as NTS Sessions 1–4 and elseq 1–5.

[15] Sherburne also stated that tracks such as "Psin AM" contained "sullen synths" that call back to Boards of Canada's Hi Scores EP.

[16] Andrew Ryce's review of Sign for Resident Advisor called "F7" one of Autechre's most "gorgeous" tracks, and that it was similar in composition to "known(1)" from Oversteps.

Writing for The Guardian, Tayyab Amin wrote that the melodies on Sign took prominence during the album, and that it was a "dense and viscous record with synthetic textures that hold great depth".

[17] Charlie Frame, writing for The Quietus commented that "Gr4" was "perhaps the prettiest track" and that it "showcases see-sawing synths that keen like a string quartet".

[29] Reviewing Sign for AllMusic, Paul Simpson commented that some tracks lacked form and were not unique and distinctive enough to be memorable for listeners.

[16] Nick Roseblade of Clash gave a positive review, noting the album's more melodic nature compared to past projects by the duo.

[14] Writing for The Quietus, Charlie Frame called the album a "welcome detour" and felt it proved Autechre were "in tune with their audience".

"[15] Joey Arnone of Under the Radar commented on the duo's ability to create confusing atmospheres and soundscapes, and said that the tracks on Sign were "chaotic and ethereal, harsh and euphoric, mechanical and biological" all at the same time.

He also stated how Autechre "continue to beguile and confound" and called Sign the duo's "most flat-out gorgeous album in ages".