During this time he was already known as a highly respected singer on the international music scene since the late 90’s due to four successful records with the power metal band At Vance and his participation in top sellers as Tobias Sammet's Avantasia and many other well known productions in the hard rock and metal scene.

Co-produced and mixed by top producer Sascha Paeth at Gate Studios/Germany the debut album 'Out in the cold' was released in spring 2005 and reviewed as 'Album of the month' in a wide range of rock magazines all over the world. It was also elected by melodicrock.com as 'Song of the year' and 'Ballad of the year' with the songs 'What if I' and 'Into the light'.

Soon the project turned into a full band line-up with Armin Donderer on bass, Mario Reck on guitar, Jürgen Wüst on keyboards and the Italian drummer Dario Ciccioni who replaced studio drummer Bodo Schopf and already worked with Oliver on the production for 'Genius Rock Opera'.

In mid 2005 the band played their first single shows and festivals in Germany and got the chance in summer 2006 to be touring over Europe for the first time as support for rock legend Toto.

In autumn 2006 the band went back to the studio to record the second album 'Home' with a slightly rougher and modernized band sound. Released in spring 2007 the album again received great critics and with songs like 'Coming home to you', 'The sun's still rising' or the soulful ballad 'Crying' the band composed classic and typical Hartmann tracks that still remain in the live setlist today.

The release of the album was followed by two support tours for House Of Lords in early spring 2007 and for The Hooters in summer 2007. During this second tour the band played their material as acoustic versions for the first time. Because of all the positive feedback and due to the fact that the whole band felt very comfortable with that sound the idea was born to record and film the songs for the next release. In September 2007 the band played two exclusive shows in the intimate atmosphere of the old German varieté theater 'Pegasus' in Bensheim/Germany. Both shows were filmed and recorded for the live DVD/CD 'Handmade' which was released in spring 2008. It's outstanding material like real 'handmade' versions of the first two studio albums and previously unreleased tracks and a cover version of John Miles' 'Music'. Straight away it captivated critics and fans worldwide and received great reviews in the global press. During the following months the band played a club tour through Germany with the same line up and became a real insider's tip on the international rock scene.

After Oliver's world wide tour in summer 2008 as guitarist and singer for Tobias Sammet’s Avantasia and several European shows with Hartmann as special guest for Edguy in spring 2009, the third album '3' was released in late 2009 on the new founded and artist owned record label SONIC 11. Again it got great reviews from the rock press and with tracks like 'Right here right now', 'Don't give up your dream' and the duet 'Brothers' featuring Tobias Sammet on vocals the album is continuing with what Hartmann already created with 'Out in the cold' and 'Home': Modern and unique melodic rock.

After the release of '3' the band played numerous shows and festivals and was asked to be special guest on tours with bands such as Mother's Finest, Uriah Heep and Y&T.

In summer 2010 keyboard player Jürgen Wüst left the band to concentrate more on his solo project. The band decided to play their live shows as a four piece band without a keyboard player from then on.

Oliver and the band started again to write songs in mid 2011 for a new studio album of Hartmann. And in April 2012, right after Oliver had been touring with the successful live project 'Rock Meets Classic', the recordings for “Balance” were completed. This fourth album, released by Avenue of Allies Label in June 2012, produced top melodic Rock music with a modern approach and international class. It was often reviewed as 'the band's best album so far' including highlights like the fast opener 'All My Life' and the exciting ballad 'After The Love Is Gone', which have also been released as videoclips. Other remarkable songs are the powerful and diverse 'Save me' and the stunning cover of Tears for Fears' hit 'Shout' which has been remixed again as a digital bonus track.

In summer 2012 Hartmann was again special guest on Toto's tour in Germany - the last concerts with the band for drummer and former member Dario Ciccioni who got married and decided to move to New York. After a few auditions Markus Kullmann (Voodoo Circle, Desperadoz, Glenn Hughes) joined the band as the new drummer in autumn to play his first gigs with Hartmann on a double headliner tour in November and December 2012 with the German hard rock act Jaded Heart.

After Oliver's second tour with 'Rock meets Classic' in early spring 2013 and his world tour with Avantasia during spring/summer 2013 the band is already working again on new songs for the next studio album of Hartmann.

Seven years and five albums later, this compilation is putting together the best and most popular tracks of the band's career. So far. Until now. It's not finished there. We're sure THE BEST IS YET TO COME…