The Immersive Audio feature in the QC Ultras is compatible with iPhone 15, requiring the Bose app for optimal performance.

QC45s include a 3.5mm to 2.5mm cable, but it is too short for desktop use, limiting its practicality.

The QC Ultras lack a power switch and have a slow firmware, leading to extended startup times and an annoying proximity-sensor standby mode.

These headphones use AAA batteries, which can be replaced with rechargeables, ensuring convenience and longevity without dealing with non-serviceable battery packs.

QC15s remain preferred for detailed sound quality, even for gaming and watching TV over newer models like QC45s and Sony XM4s.

The lightweight design is frequently praised, especially for long-term use during travel or work.

QC45s were found for $200 at Costco, considered a good deal compared to other models like the Sony XM4 and XM5.

Some users found the audio quality of QC45s inferior to QC15s, describing the sound as flat and hollow, particularly when playing music.

Users report a delay when using cabled input with the QC Ultras, which might affect real-time audio applications.

Despite extensive use, many owners report the noise-canceling feature and sound quality remain exceptional, even after a decade.

QC15 headphones have clearer sound and are louder at the same volume compared to QC45, even in wired mode.

The QC Ultras have about 20% better noise cancellation for high-frequency sounds compared to the QC SE, though the SE might excel in blocking lower frequencies.

The QC Ultras use aptX Adaptive codec, but without AAC support, they offer little advantage for iPhone users, making them similar to the QC SE in such cases.

Modifying QC-15 headphones with Dynamat-like material and sound deadening batting can improve sound clarity and noise reduction by reducing micro echoes and shell vibrations.

Bluetooth adapters for QC15s are available, such as Twelve South's Airfly, allowing these wired headphones to function wirelessly.

The headband on the QC15s can sometimes snap, particularly near the pivot point, even with normal use.

The ear cushions have been replaced multiple times by different users, often opting for brands like Wicked Cushions, which are noted for their durability and stitching.