Carl Broemel and Bo Koster join the band

In January 2004 Carl Broemel and keyboardist Bo Koster replaced Johnny Quaid and Danny Cash respectively.

Auditions
In a 2005 interview with The Georgia Straight Jim James how he at first thought My Morning Jacket would cease to be, but then decided to audition people.
"That whole period was like some sort of magic trick, I thought we were going to stop being a band. Instead we decided to audition people. The first two guys we saw [guitarist Carl Broemel and keyboardist Bo Koster] were so nice that we decided to go ahead and try them out. From the first show, they fucking went for it, and that really inspired the rest of us."
 - Jim James
(The Georgia Straight interview, November 2005)

According to 2007 Magnet Magazine interview a friend suggested the band hold auditions for the two vacated spots, however James was initially pessimistic about the idea. This is confirmed in an 2008 Spin Magazine interview, that explains how the band reluctantly set up open auditions in an L.A. rehearsal space, however according to the interview the first two players to walk in were Broemel and Koster and they knew every song.
"When they came in we were so fucking burnt, but they were like kids in a candy store and their excitement just lifted us."
- Jim James
(Spin interview, May 2008)
"They knew everything, more than we did. They just fucking nailed it. Anything could’ve happened. They could’ve been dickheads or drug addicts. I felt like Bo and Carl were sent to us to keep it going."
- Jim James
(Magnet Magazine interview, September 2007)

In an 2011 interview with The Santa Barbara Independent Carl Broemel explains how he hooked up with the band after hearing that Johnny Quaid and Danny Cash were leaving.
"I was living in Los Angeles — I moved from Indiana to Los Angeles a couple years after school was done — and I was playing in bands out here and touring around with whoever and doing a little bit of session work. I got integrated with people that were looking to fill spots in bands and they knew who I was, which was a good thing. So when John [Quaid] and Dan [Cash] decided to leave they came out here looking for new people and I caught wind of it through a mutual friend of ours. So I became familiar with the band and went in and played with them and did a little trial run just to meet everybody."
- Carl BroemelLänk(The Santa Barbara Independent interview, June 2011)

In the same 2011 interview Broemel explains that he hadn't really heard of the band, until a friend helped get him interested.
"I hadn’t really heard the band, but my good friend Cameron was always freaking out about My Morning Jacket, so he played me some music and I thought it was really interesting. But I had heard a song on KCRW maybe a month or two before the audition, and I didn’t know who the band was, and I was kind of frustrated with my present musical position at the time and I remember hearing that and being like, ‘man, I wish I could do something like that’ and kind of getting misty. So, when I was preparing to go in and learn the songs that song came up. I was already excited about the music, but when that happened I felt like the universe had heard me somehow. So I met everybody and they were all great people. I felt like I got pulled out of a bad situation into an unbelievable situation."
- Carl BroemelLänk(The Santa Barbara Independent interview, June 2011)

Bo Koster on the other hand was, according to a 2007 Magnet Magazine interview, recommended to the band by singer/songwriter Bobby Bare Jr. In a Rotoworld interview, Koster explains that he was living LA and working with documentary television before joining My Morning Jacket. During this period of time Koster also played various gigs around town.
"I used to play in a lot of different situations. Various jazz stuff, including a Bossa Nova band, singer songwriter stuff, rock bands, and I wrote music and played with a live hip hop band from east LA for a while. A lot of soul/R&B gigs, at a place called the Temple Bar. I went on the road a couple of times as a sideman, with an artist called Kenna and a Texas blues band. Then I worked on a project headed up by Mike Garson and a bunch of great keyboardists for Yamaha pianos for two years. Basically we made music for their Disklavier, which is a piano that plays by itself. "
- Bo Koster
(Rotoworld interview, February 2009)

In the same Rotoworld interview Koster says that he doesn't think it was a coincidence that he found My Morning Jacket very soon after that period.
"I always wanted to find a situation that was creatively inspiring, with people who loved and had a similar attitude about music that I had. After a long search and struggle I finally found that, and I feel very lucky for it."
- Bo Koster
(Rotoworld interview, February 2009)

A few other players auditioned for the spots as well, but although, according to James none of them worked.
"We tried out maybe eight or nine people, and (other than Broemel and Koster) a couple of them were OK. But none of them really worked. The whole rest of the audition went just like I thought it would."
- Jim James
(Magnet Magazine interview, September 2007)
"Auditions and stuff like that are stressful. You want to be like ‘Pick me! Pick me! Pick me!’ but you don’t want to be annoying. I don’t think anybody in the band at that point had played with anybody they didn’t know, so it was an awkward situation for them and an awkward situation for us."
- Carl BroemelLänk(The Santa Barbara Independent interview, June 2011)

As stated in a Spin Magazine interview a week or so later after the audition Bo Koster got a call from Jim James.
"Jim pulled one of those 'Man we really like you, thought you were a good player and all, buuuut... we'd like you to come on tour with us.' And nothing has changed since, Jim is still fucking with me."
- Bo Koster
(Spin interview, May 2008)

Within weeks after the January auditions the band was back on the road.

Difference and evolution
"The biggest thing is it's just a different band altogether really kind of reinventing how we do it all. Carl and Bo are just so talented, it's challenged me to be a better musician and to think about things musically in a way I hadn't before instead of just doing it and going by just feel."
- Tom Blankenship
(PopMatters Interview October 2005)
"They're really versatile. They can both sing, and that's something we never had. Carl can play sax and guitar and pedal steel. And Bo is just an amazing keyboard player. But most of all their amazing newness and freshness has re-upped our energy. We've been doing it a long time and to have them come in and sock us full of energy again, to see them so excited, just kind of fires up the whole machine. Their ability to take what I'm trying to explain to them and just do it immediately, without thinking about it, is just amazing. We work better. We're running smoother."
Jim James
PopMatters Interview, October 2005)
“Had I stayed or had John and Danny stayed, I don’t know if they’d be where they are today. This band, the way it is now, is the way it’s supposed to be. Pete’s a better drummer than me, Carl’s a better guitar player than Johnny, Bo is leaps and bounds better than Danny on keys. This band is amazing.”
- Christopher "KC" Guetig
(Magnet Magazine interview, September 2007)