Online mastering services such as emastered.com; landr.com; ariamastering.com; cloudbounce.com and more use an algorithm to master tracks – meaning your music will typically not be heard by human ears – instead, your track is run through some software that automatically makes adjustments to volume, compression and EQ based on a formula the algorithm applies. Algorithm-based mastering can come in handy when you want to get a glimpse at your track's potential or when you want to check a mix against standardized processing. You may have a quick demo mix that you think sounds good, and perhaps you want to add some overall compression and limiting to get that “radio sound” through a volume boost. However, these mastering services do tend to work by applying a rubber stamp to each track because no one is actually listening. When you try my mastering studio, you are partnering with a professional mastering engineer and will receive the personal attention your music deserves, as well as the experience and specialized equipment that come along with a mastering engineer’s touch.  Additionally, a mastering engineer will be far more likely to offer the ability to make changes to a master after the first pass, giving you more freedom in getting the sound you’re after. You can read more about algorithm-based online mastering services here.  If you’re unsure, you’re more than welcome to request a free mastering sample, and compare the services yourself.